diff --git a/models/issues/comment.go b/models/issues/comment.go
index 4fdb0c1808fb4..65832b9226a50 100644
--- a/models/issues/comment.go
+++ b/models/issues/comment.go
@@ -115,6 +115,7 @@ const (
 	CommentTypeUnpin // 37 unpin Issue/PullRequest
 
 	CommentTypeChangeTimeEstimate // 38 Change time estimate
+	CommentTypeChangePRFlowType // 39 Change pull request's flow type
 )
 
 var commentStrings = []string{
@@ -157,6 +158,7 @@ var commentStrings = []string{
 	"pin",
 	"unpin",
 	"change_time_estimate",
+	"change_flow_type",
 }
 
 func (t CommentType) String() string {
diff --git a/models/issues/pull.go b/models/issues/pull.go
index 4c25b6f0c8494..86ea78f243bdf 100644
--- a/models/issues/pull.go
+++ b/models/issues/pull.go
@@ -113,6 +113,30 @@ const (
 	PullRequestFlowAGit
 )
 
+var PullRequestFlowMap map[PullRequestFlow]string = map[PullRequestFlow]string{
+	PullRequestFlowGithub: "github",
+	PullRequestFlowAGit:   "agit",
+}
+var PullRequestFlowTypeUnknown error = errors.New("Unknown pull request type")
+
+func PullRequestFlowFromString(strtype string) (PullRequestFlow, error) {
+	for k, v := range PullRequestFlowMap {
+		if v == strtype {
+			return k, nil
+		}
+	}
+
+	return 0, PullRequestFlowTypeUnknown
+}
+
+func PullRequestFlowTypeToString(flow PullRequestFlow) string {
+	v, ok := PullRequestFlowMap[flow]
+	if ok {
+		return v
+	}
+	return ""
+}
+
 // PullRequest represents relation between pull request and repositories.
 type PullRequest struct {
 	ID              int64 `xorm:"pk autoincr"`
@@ -462,6 +486,18 @@ func (pr *PullRequest) IsFromFork() bool {
 	return pr.HeadRepoID != pr.BaseRepoID
 }
 
+func (pr *PullRequest) ConvertToAgitPullRequest(ctx context.Context, doer *user_model.User) (err error) {
+	if pr.IsAgitFlow() {
+		return nil
+	}
+
+	pr.Flow = PullRequestFlowAGit
+	pr.HeadRepoID = pr.BaseRepoID
+	pr.HeadBranch = doer.LowerName + "/" + pr.HeadBranch
+
+	return pr.UpdateColsIfNotMerged(ctx, "flow", "head_repo_id", "head_branch")
+}
+
 // NewPullRequest creates new pull request with labels for repository.
 func NewPullRequest(ctx context.Context, repo *repo_model.Repository, issue *Issue, labelIDs []int64, uuids []string, pr *PullRequest) (err error) {
 	ctx, committer, err := db.TxContext(ctx)
diff --git a/modules/structs/pull.go b/modules/structs/pull.go
index f53d6adafce3a..e4c42fb168d61 100644
--- a/modules/structs/pull.go
+++ b/modules/structs/pull.go
@@ -60,6 +60,9 @@ type PullRequest struct {
 	Closed *time.Time `json:"closed_at"`
 
 	PinOrder int `json:"pin_order"`
+
+	// swagger:enum["agit","github"]
+	Flow string `json:"flow"`
 }
 
 // PRBranchInfo information about a branch
@@ -107,6 +110,7 @@ type EditPullRequestOption struct {
 	Deadline            *time.Time `json:"due_date"`
 	RemoveDeadline      *bool      `json:"unset_due_date"`
 	AllowMaintainerEdit *bool      `json:"allow_maintainer_edit"`
+	FlowType            string     `json:"flow_type"`
 }
 
 // ChangedFile store information about files affected by the pull request
diff --git a/routers/api/v1/repo/pull.go b/routers/api/v1/repo/pull.go
index e05b9b165c2fc..7bf7c148e690d 100644
--- a/routers/api/v1/repo/pull.go
+++ b/routers/api/v1/repo/pull.go
@@ -777,6 +777,46 @@ func EditPullRequest(ctx *context.APIContext) {
 		notify_service.PullRequestChangeTargetBranch(ctx, ctx.Doer, pr, form.Base)
 	}
 
+	// change pull request type from branch or from AGit
+	if !pr.HasMerged && len(form.FlowType) != 0 {
+		flow, err := issues_model.PullRequestFlowFromString(form.FlowType)
+		if err != nil {
+			ctx.APIErrorInternal(err)
+			return
+		}
+		err = nil
+		if !issue.IsPoster(ctx.Doer.ID) && !ctx.Repo.CanWrite(unit.TypeCode) {
+			// not implemented
+			ctx.Status(http.StatusForbidden)
+			return
+		}
+		if flow != pr.Flow {
+			switch flow {
+			case issues_model.PullRequestFlowGithub:
+				// not implemented
+				ctx.Status(http.StatusForbidden)
+				return
+			case issues_model.PullRequestFlowAGit:
+				err = pull_service.ChangePullRequestFlowToAgit(ctx, pr, ctx.Doer)
+			}
+		}
+		if err != nil {
+			if issues_model.IsErrPullRequestAlreadyExists(err) {
+				ctx.APIError(http.StatusConflict, err)
+				return
+			} else if issues_model.IsErrIssueIsClosed(err) {
+				ctx.APIError(http.StatusUnprocessableEntity, err)
+				return
+			} else if pull_service.IsErrPullRequestHasMerged(err) {
+				ctx.APIError(http.StatusConflict, err)
+				return
+			}
+			ctx.APIErrorInternal(err)
+			return
+		}
+		notify_service.PullRequestChangeFlowType(ctx, ctx.Doer, pr)
+	}
+
 	// update allow edits
 	if form.AllowMaintainerEdit != nil {
 		if err := pull_service.SetAllowEdits(ctx, ctx.Doer, pr, *form.AllowMaintainerEdit); err != nil {
diff --git a/services/actions/notifier.go b/services/actions/notifier.go
index d10cc0ab34419..6220cd8f9323a 100644
--- a/services/actions/notifier.go
+++ b/services/actions/notifier.go
@@ -688,6 +688,32 @@ func (n *actionsNotifier) PullRequestSynchronized(ctx context.Context, doer *use
 		Notify(ctx)
 }
 
+func (n *actionsNotifier) PullRequestChangeFlowType(ctx context.Context, doer *user_model.User, pr *issues_model.PullRequest) {
+	ctx = withMethod(ctx, "PullRequestChangeFlowType")
+
+	if err := pr.LoadIssue(ctx); err != nil {
+		log.Error("LoadAttributes: %v", err)
+		return
+	}
+
+	if err := pr.Issue.LoadRepo(ctx); err != nil {
+		log.Error("pr.Issue.LoadRepo: %v", err)
+		return
+	}
+
+	permission, _ := access_model.GetUserRepoPermission(ctx, pr.Issue.Repo, pr.Issue.Poster)
+	newNotifyInput(pr.Issue.Repo, doer, webhook_module.HookEventPullRequest).
+		WithPayload(&api.PullRequestPayload{
+			Action: api.HookIssueEdited,
+			Index:  pr.Issue.Index,
+			PullRequest: convert.ToAPIPullRequest(ctx, pr, nil),
+			Repository:  convert.ToRepo(ctx, pr.Issue.Repo, permission),
+			Sender:      convert.ToUser(ctx, doer, nil),
+		}).
+		WithPullRequest(pr).
+		Notify(ctx)
+}
+
 func (n *actionsNotifier) PullRequestChangeTargetBranch(ctx context.Context, doer *user_model.User, pr *issues_model.PullRequest, oldBranch string) {
 	ctx = withMethod(ctx, "PullRequestChangeTargetBranch")
 
diff --git a/services/convert/pull.go b/services/convert/pull.go
index 4acbd880dc65c..7732bdccaaffc 100644
--- a/services/convert/pull.go
+++ b/services/convert/pull.go
@@ -97,6 +97,7 @@ func ToAPIPullRequest(ctx context.Context, pr *issues_model.PullRequest, doer *u
 		Created:        pr.Issue.CreatedUnix.AsTimePtr(),
 		Updated:        pr.Issue.UpdatedUnix.AsTimePtr(),
 		PinOrder:       util.Iif(apiIssue.PinOrder == -1, 0, apiIssue.PinOrder),
+		Flow:           issues_model.PullRequestFlowTypeToString(pr.Flow),
 
 		// output "[]" rather than null to align to github outputs
 		RequestedReviewers:      []*api.User{},
diff --git a/services/forms/user_form_hidden_comments.go b/services/forms/user_form_hidden_comments.go
index 76382ddfdde68..1378e9fe2922a 100644
--- a/services/forms/user_form_hidden_comments.go
+++ b/services/forms/user_form_hidden_comments.go
@@ -36,6 +36,7 @@ var hiddenCommentTypeGroups = hiddenCommentTypeGroupsType{
 	"branch": {
 		/*11*/ issues_model.CommentTypeDeleteBranch,
 		/*25*/ issues_model.CommentTypeChangeTargetBranch,
+		/*39*/ issues_model.CommentTypeChangePRFlowType,
 	},
 	"time_tracking": {
 		/*12*/ issues_model.CommentTypeStartTracking,
diff --git a/services/notify/notifier.go b/services/notify/notifier.go
index 875a70e5644a7..2433e31e1bd18 100644
--- a/services/notify/notifier.go
+++ b/services/notify/notifier.go
@@ -49,6 +49,7 @@ type Notifier interface {
 	PullRequestReview(ctx context.Context, pr *issues_model.PullRequest, review *issues_model.Review, comment *issues_model.Comment, mentions []*user_model.User)
 	PullRequestCodeComment(ctx context.Context, pr *issues_model.PullRequest, comment *issues_model.Comment, mentions []*user_model.User)
 	PullRequestChangeTargetBranch(ctx context.Context, doer *user_model.User, pr *issues_model.PullRequest, oldBranch string)
+	PullRequestChangeFlowType(ctx context.Context, doer *user_model.User, pr *issues_model.PullRequest)
 	PullRequestPushCommits(ctx context.Context, doer *user_model.User, pr *issues_model.PullRequest, comment *issues_model.Comment)
 	PullReviewDismiss(ctx context.Context, doer *user_model.User, review *issues_model.Review, comment *issues_model.Comment)
 
diff --git a/services/notify/notify.go b/services/notify/notify.go
index 2416cbd2e0830..2877c647c6ab3 100644
--- a/services/notify/notify.go
+++ b/services/notify/notify.go
@@ -155,6 +155,13 @@ func PullRequestChangeTargetBranch(ctx context.Context, doer *user_model.User, p
 	}
 }
 
+// PullRequestChangeFlowType notifies when a pull request's source branch was changed
+func PullRequestChangeFlowType(ctx context.Context, doer *user_model.User, pr *issues_model.PullRequest) {
+	for _, notifier := range notifiers {
+		notifier.PullRequestChangeFlowType(ctx, doer, pr)
+	}
+}
+
 // PullRequestPushCommits notifies when push commits to pull request's head branch
 func PullRequestPushCommits(ctx context.Context, doer *user_model.User, pr *issues_model.PullRequest, comment *issues_model.Comment) {
 	for _, notifier := range notifiers {
diff --git a/services/notify/null.go b/services/notify/null.go
index c3085d7c9eb0a..bb92fe35d509c 100644
--- a/services/notify/null.go
+++ b/services/notify/null.go
@@ -70,6 +70,10 @@ func (*NullNotifier) PullRequestSynchronized(ctx context.Context, doer *user_mod
 func (*NullNotifier) PullRequestChangeTargetBranch(ctx context.Context, doer *user_model.User, pr *issues_model.PullRequest, oldBranch string) {
 }
 
+// PullRequestChangeFlowType places a place holder function
+func (*NullNotifier) PullRequestChangeFlowType(ctx context.Context, doer *user_model.User, pr *issues_model.PullRequest) {
+}
+
 // PullRequestPushCommits notifies when push commits to pull request's head branch
 func (*NullNotifier) PullRequestPushCommits(ctx context.Context, doer *user_model.User, pr *issues_model.PullRequest, comment *issues_model.Comment) {
 }
diff --git a/services/pull/pull.go b/services/pull/pull.go
index 2829e15441081..eabe0b239c6ba 100644
--- a/services/pull/pull.go
+++ b/services/pull/pull.go
@@ -247,6 +247,58 @@ func (err ErrPullRequestHasMerged) Error() string {
 		err.ID, err.IssueID, err.HeadRepoID, err.BaseRepoID, err.HeadBranch, err.BaseBranch)
 }
 
+// ChangePullRequestFlowToAgit changes the source branch of this pull request, as the given user
+func ChangePullRequestFlowToAgit(ctx context.Context, pr *issues_model.PullRequest, doer *user_model.User) (err error) {
+	releaser, err := globallock.Lock(ctx, getPullWorkingLockKey(pr.ID))
+	if err != nil {
+		log.Error("lock.Lock(): %v", err)
+		return fmt.Errorf("lock.Lock: %w", err)
+	}
+	defer releaser()
+
+	// Current target branch is already the same
+	if pr.Flow == issues_model.PullRequestFlowAGit {
+		return nil
+	}
+
+	if pr.Issue.IsClosed {
+		return issues_model.ErrIssueIsClosed{
+			ID:     pr.Issue.ID,
+			RepoID: pr.Issue.RepoID,
+			Index:  pr.Issue.Index,
+			IsPull: true,
+		}
+	}
+
+	if pr.HasMerged {
+		return ErrPullRequestHasMerged{
+			ID:         pr.ID,
+			IssueID:    pr.Index,
+			HeadRepoID: pr.HeadRepoID,
+			BaseRepoID: pr.BaseRepoID,
+			HeadBranch: pr.HeadBranch,
+			BaseBranch: pr.BaseBranch,
+		}
+	}
+
+	if err = pr.ConvertToAgitPullRequest(ctx, doer); err != nil {
+		return fmt.Errorf("Failed to convert PR to AGit: %w", err)
+	}
+
+	// Create comment
+	options := &issues_model.CreateCommentOptions{
+		Type:   issues_model.CommentTypeChangePRFlowType,
+		Doer:   doer,
+		Repo:   pr.Issue.Repo,
+		Issue:  pr.Issue,
+	}
+	if _, err = issues_model.CreateComment(ctx, options); err != nil {
+		return fmt.Errorf("CreateChangeSourceBranchComment: %w", err)
+	}
+
+	return nil
+}
+
 // ChangeTargetBranch changes the target branch of this pull request, as the given user.
 func ChangeTargetBranch(ctx context.Context, pr *issues_model.PullRequest, doer *user_model.User, targetBranch string) (err error) {
 	releaser, err := globallock.Lock(ctx, getPullWorkingLockKey(pr.ID))
@@ -1003,6 +1055,10 @@ func getAllCommitStatus(ctx context.Context, gitRepo *git.Repository, pr *issues
 	return statuses, lastStatus, err
 }
 
+func IsBranchEqual(ctx context.Context, gitRepo *git.Repository, branch1, branch2 string) (bool, error) {
+	return false, nil
+}
+
 // IsHeadEqualWithBranch returns if the commits of branchName are available in pull request head
 func IsHeadEqualWithBranch(ctx context.Context, pr *issues_model.PullRequest, branchName string) (bool, error) {
 	var err error
diff --git a/services/webhook/notifier.go b/services/webhook/notifier.go
index 672abd5c95d0e..b4297548bd2f1 100644
--- a/services/webhook/notifier.go
+++ b/services/webhook/notifier.go
@@ -731,6 +731,26 @@ func (m *webhookNotifier) PullRequestChangeTargetBranch(ctx context.Context, doe
 	}
 }
 
+func (m *webhookNotifier) PullRequestChangeFlowType(ctx context.Context, doer *user_model.User, pr *issues_model.PullRequest) {
+	if err := pr.LoadIssue(ctx); err != nil {
+		log.Error("LoadIssue: %v", err)
+		return
+	}
+
+	issue := pr.Issue
+
+	mode, _ := access_model.GetUserRepoPermission(ctx, issue.Repo, issue.Poster)
+	if err := PrepareWebhooks(ctx, EventSource{Repository: issue.Repo}, webhook_module.HookEventPullRequest, &api.PullRequestPayload{
+		Action: api.HookIssueEdited,
+		Index:  issue.Index,
+		PullRequest: convert.ToAPIPullRequest(ctx, pr, doer),
+		Repository:  convert.ToRepo(ctx, issue.Repo, mode),
+		Sender:      convert.ToUser(ctx, doer, nil),
+	}); err != nil {
+		log.Error("PrepareWebhooks [pr: %d]: %v", pr.ID, err)
+	}
+}
+
 func (m *webhookNotifier) PullRequestReview(ctx context.Context, pr *issues_model.PullRequest, review *issues_model.Review, comment *issues_model.Comment, mentions []*user_model.User) {
 	var reviewHookType webhook_module.HookEventType
 
diff --git a/templates/swagger/v1_json.tmpl b/templates/swagger/v1_json.tmpl
index 323e0d64ac567..52caee6922191 100644
--- a/templates/swagger/v1_json.tmpl
+++ b/templates/swagger/v1_json.tmpl
@@ -24173,6 +24173,10 @@
           "format": "date-time",
           "x-go-name": "Deadline"
         },
+        "flow_type": {
+          "type": "string",
+          "x-go-name": "FlowType"
+        },
         "labels": {
           "type": "array",
           "items": {
@@ -26718,6 +26722,10 @@
           "format": "date-time",
           "x-go-name": "Deadline"
         },
+        "flow": {
+          "type": "string",
+          "x-go-name": "Flow"
+        },
         "head": {
           "$ref": "#/definitions/PRBranchInfo"
         },