diff --git a/api/services/dataset_service.py b/api/services/dataset_service.py
index 1ea6c4e1c3..b208e394b0 100644
--- a/api/services/dataset_service.py
+++ b/api/services/dataset_service.py
@@ -1696,13 +1696,18 @@ class DocumentService:
             for document in documents
             if document.data_source_type == "upload_file" and document.data_source_info_dict
         ]
-        if dataset.doc_form is not None:
-            batch_clean_document_task.delay(document_ids, dataset.id, dataset.doc_form, file_ids)
 
+        # Delete documents first, then dispatch cleanup task after commit
+        # to avoid deadlock between main transaction and async task
         for document in documents:
             db.session.delete(document)
         db.session.commit()
 
+        # Dispatch cleanup task after commit to avoid lock contention
+        # Task cleans up segments, files, and vector indexes
+        if dataset.doc_form is not None:
+            batch_clean_document_task.delay(document_ids, dataset.id, dataset.doc_form, file_ids)
+
     @staticmethod
     def rename_document(dataset_id: str, document_id: str, name: str) -> Document:
         assert isinstance(current_user, Account)