diff --git a/models/issues/pull_list.go b/models/issues/pull_list.go
index 6c9e8c4e0..9d361c5c5 100644
--- a/models/issues/pull_list.go
+++ b/models/issues/pull_list.go
@@ -52,13 +52,16 @@ func listPullRequestStatement(baseRepoID int64, opts *PullRequestsOptions) (*xor
 
 // GetUnmergedPullRequestsByHeadInfo returns all pull requests that are open and has not been merged
 // by given head information (repo and branch).
-func GetUnmergedPullRequestsByHeadInfo(repoID int64, branch string) ([]*PullRequest, error) {
+// arg `includeClosed` controls whether the SQL returns closed PRs
+func GetUnmergedPullRequestsByHeadInfo(repoID int64, branch string, includeClosed bool) ([]*PullRequest, error) {
 	prs := make([]*PullRequest, 0, 2)
-	return prs, db.GetEngine(db.DefaultContext).
-		Where("head_repo_id = ? AND head_branch = ? AND has_merged = ? AND issue.is_closed = ? AND flow = ?",
-			repoID, branch, false, false, PullRequestFlowGithub).
+	sess := db.GetEngine(db.DefaultContext).
 		Join("INNER", "issue", "issue.id = pull_request.issue_id").
-		Find(&prs)
+		Where("head_repo_id = ? AND head_branch = ? AND has_merged = ? AND flow = ?", repoID, branch, false, PullRequestFlowGithub)
+	if !includeClosed {
+		sess.Where("issue.is_closed = ?", false)
+	}
+	return prs, sess.Find(&prs)
 }
 
 // CanMaintainerWriteToBranch check whether user is a maintainer and could write to the branch
@@ -71,7 +74,7 @@ func CanMaintainerWriteToBranch(p access_model.Permission, branch string, user *
 		return false
 	}
 
-	prs, err := GetUnmergedPullRequestsByHeadInfo(p.Units[0].RepoID, branch)
+	prs, err := GetUnmergedPullRequestsByHeadInfo(p.Units[0].RepoID, branch, false)
 	if err != nil {
 		return false
 	}
diff --git a/models/issues/pull_test.go b/models/issues/pull_test.go
index 8ce8eecc4..bcd33329e 100644
--- a/models/issues/pull_test.go
+++ b/models/issues/pull_test.go
@@ -118,7 +118,7 @@ func TestHasUnmergedPullRequestsByHeadInfo(t *testing.T) {
 
 func TestGetUnmergedPullRequestsByHeadInfo(t *testing.T) {
 	assert.NoError(t, unittest.PrepareTestDatabase())
-	prs, err := issues_model.GetUnmergedPullRequestsByHeadInfo(1, "branch2")
+	prs, err := issues_model.GetUnmergedPullRequestsByHeadInfo(1, "branch2", false)
 	assert.NoError(t, err)
 	assert.Len(t, prs, 1)
 	for _, pr := range prs {
diff --git a/routers/web/repo/issue.go b/routers/web/repo/issue.go
index 47b499a3c..3715320f1 100644
--- a/routers/web/repo/issue.go
+++ b/routers/web/repo/issue.go
@@ -1420,11 +1420,12 @@ func ViewIssue(ctx *context.Context) {
 	}
 
 	var (
-		role         issues_model.RoleDescriptor
-		ok           bool
-		marked       = make(map[int64]issues_model.RoleDescriptor)
-		comment      *issues_model.Comment
-		participants = make([]*user_model.User, 1, 10)
+		role                 issues_model.RoleDescriptor
+		ok                   bool
+		marked               = make(map[int64]issues_model.RoleDescriptor)
+		comment              *issues_model.Comment
+		participants         = make([]*user_model.User, 1, 10)
+		latestCloseCommentID int64
 	)
 	if ctx.Repo.Repository.IsTimetrackerEnabled(ctx) {
 		if ctx.IsSigned {
@@ -1622,9 +1623,15 @@ func ViewIssue(ctx *context.Context) {
 			comment.Type == issues_model.CommentTypeStopTracking {
 			// drop error since times could be pruned from DB..
 			_ = comment.LoadTime()
+		} else if comment.Type == issues_model.CommentTypeClose {
+			// record ID of latest closed comment.
+			// if PR is closed, the comments whose type is CommentTypePullRequestPush(29) after latestCloseCommentID won't be rendered.
+			latestCloseCommentID = comment.ID
 		}
 	}
 
+	ctx.Data["LatestCloseCommentID"] = latestCloseCommentID
+
 	// Combine multiple label assignments into a single comment
 	combineLabelComments(issue)
 
diff --git a/routers/web/repo/pull.go b/routers/web/repo/pull.go
index 78c935a8c..4f9968773 100644
--- a/routers/web/repo/pull.go
+++ b/routers/web/repo/pull.go
@@ -587,7 +587,7 @@ func PrepareViewPullInfo(ctx *context.Context, issue *issues_model.Issue) *git.C
 	ctx.Data["HeadBranchCommitID"] = headBranchSha
 	ctx.Data["PullHeadCommitID"] = sha
 
-	if pull.HeadRepo == nil || !headBranchExist || headBranchSha != sha {
+	if pull.HeadRepo == nil || !headBranchExist || (!pull.Issue.IsClosed && (headBranchSha != sha)) {
 		ctx.Data["IsPullRequestBroken"] = true
 		if pull.IsSameRepo() {
 			ctx.Data["HeadTarget"] = pull.HeadBranch
diff --git a/services/pull/pull.go b/services/pull/pull.go
index 0d260c93b..a19e88b33 100644
--- a/services/pull/pull.go
+++ b/services/pull/pull.go
@@ -257,7 +257,7 @@ func AddTestPullRequestTask(doer *user_model.User, repoID int64, branch string,
 		// If you don't let it run all the way then you will lose data
 		// TODO: graceful: AddTestPullRequestTask needs to become a queue!
 
-		prs, err := issues_model.GetUnmergedPullRequestsByHeadInfo(repoID, branch)
+		prs, err := issues_model.GetUnmergedPullRequestsByHeadInfo(repoID, branch, true)
 		if err != nil {
 			log.Error("Find pull requests [head_repo_id: %d, head_branch: %s]: %v", repoID, branch, err)
 			return
@@ -500,7 +500,7 @@ func (errs errlist) Error() string {
 
 // CloseBranchPulls close all the pull requests who's head branch is the branch
 func CloseBranchPulls(doer *user_model.User, repoID int64, branch string) error {
-	prs, err := issues_model.GetUnmergedPullRequestsByHeadInfo(repoID, branch)
+	prs, err := issues_model.GetUnmergedPullRequestsByHeadInfo(repoID, branch, false)
 	if err != nil {
 		return err
 	}
@@ -536,7 +536,7 @@ func CloseRepoBranchesPulls(ctx context.Context, doer *user_model.User, repo *re
 
 	var errs errlist
 	for _, branch := range branches {
-		prs, err := issues_model.GetUnmergedPullRequestsByHeadInfo(repo.ID, branch.Name)
+		prs, err := issues_model.GetUnmergedPullRequestsByHeadInfo(repo.ID, branch.Name, false)
 		if err != nil {
 			return err
 		}
diff --git a/templates/repo/issue/view_content/comments.tmpl b/templates/repo/issue/view_content/comments.tmpl
index 6054e7b86..03f48ace6 100644
--- a/templates/repo/issue/view_content/comments.tmpl
+++ b/templates/repo/issue/view_content/comments.tmpl
@@ -697,7 +697,11 @@
 				</span>
 			</div>
 		{{else if and (eq .Type 29) (or (gt .CommitsNum 0) .IsForcePush)}}
-			<div class="timeline-item event" id="{{.HashTag}}">
+			<!-- If PR is closed, the comments whose type is CommentTypePullRequestPush(29) after latestCloseCommentID won't be rendered. //-->
+			{{if and .Issue.IsClosed (gt .ID $.LatestCloseCommentID)}}
+				{{continue}}
+			{{end}}`
+			<div class="timeline-item event" id="{{.HashTag}}">`
 				<span class="badge">{{svg "octicon-repo-push"}}</span>
 				<span class="text grey muted-links">
 					{{template "shared/user/authorlink" .Poster}}