diff --git a/routers/api/v1/repo/pull.go b/routers/api/v1/repo/pull.go
index ac1f038131..445530f85b 100644
--- a/routers/api/v1/repo/pull.go
+++ b/routers/api/v1/repo/pull.go
@@ -1086,10 +1086,19 @@ func parseCompareInfo(ctx *context.APIContext, form api.CreatePullRequestOption)
 
 	ctx.Repo.PullRequest.SameRepo = isSameRepo
 	log.Trace("Repo path: %q, base branch: %q, head branch: %q", ctx.Repo.GitRepo.Path, baseBranch, headBranch)
+
 	// Check if base branch is valid.
-	if  !ctx.Repo.GitRepo.IsCommitExist(baseBranch) && !ctx.Repo.GitRepo.IsBranchExist(baseBranch) && !ctx.Repo.GitRepo.IsTagExist(baseBranch) {
-		ctx.NotFound("BaseNotExist")
-		return nil, nil, nil, "", ""
+	baseIsCommit := ctx.Repo.GitRepo.IsCommitExist(baseBranch)
+    baseIsBranch := ctx.Repo.GitRepo.IsBranchExist(baseBranch)
+    baseIsTag := ctx.Repo.GitRepo.IsTagExist(baseBranch)
+    if !baseIsCommit && !baseIsBranch && !baseIsTag {
+            // Check for short SHA usage
+            if baseCommit, _ := ctx.Repo.GitRepo.GetCommit(baseBranch); baseCommit != nil {
+                    baseBranch = baseCommit.ID.String()
+            } else {
+                    ctx.NotFound("BaseNotExist")
+                    return nil, nil, nil, "", ""
+            }
 	}
 
 	// Check if current user has fork of repository or in the same repository.
@@ -1162,13 +1171,34 @@ func parseCompareInfo(ctx *context.APIContext, form api.CreatePullRequestOption)
 	}
 
 	// Check if head branch is valid.
-	if !ctx.Repo.GitRepo.IsCommitExist(baseBranch) && !headGitRepo.IsBranchExist(headBranch) && !headGitRepo.IsTagExist(headBranch) {
-		headGitRepo.Close()
-		ctx.NotFound()
-		return nil, nil, nil, "", ""
-	}
+	headIsCommit := headGitRepo.IsBranchExist(headBranch)
+	headIsBranch := headGitRepo.IsTagExist(headBranch)
+    headIsTag := headGitRepo.IsCommitExist(baseBranch)
+    if !headIsCommit && !headIsBranch && !headIsTag {
+            // Check if headBranch is short sha commit hash
+            if headCommit, _ := headGitRepo.GetCommit(headBranch); headCommit != nil {
+                    headBranch = headCommit.ID.String()
+            } else {
+                    headGitRepo.Close()
+                    ctx.NotFound("IsRefExist", nil)
+                    return nil, nil, nil, "", ""
+            }
+    }
 
-	compareInfo, err := headGitRepo.GetCompareInfo(repo_model.RepoPath(baseRepo.Owner.Name, baseRepo.Name), baseBranch, headBranch, false, false)
+    baseBranchRef := baseBranch
+    if baseIsBranch {
+            baseBranchRef = git.BranchPrefix + baseBranch
+    } else if baseIsTag {
+            baseBranchRef = git.TagPrefix + baseBranch
+    }
+    headBranchRef := headBranch
+    if headIsBranch {
+            headBranchRef = headBranch
+    } else if headIsTag {
+            headBranchRef = headBranch
+    }
+
+	compareInfo, err := headGitRepo.GetCompareInfo(repo_model.RepoPath(baseRepo.Owner.Name, baseRepo.Name), baseBranchRef, headBranchRef, false, false)
 	if err != nil {
 		headGitRepo.Close()
 		ctx.Error(http.StatusInternalServerError, "GetCompareInfo", err)