diff --git a/apps/pm/views.py b/apps/pm/views.py
index 2ca45329..391d7f90 100644
--- a/apps/pm/views.py
+++ b/apps/pm/views.py
@@ -131,7 +131,7 @@ class MtaskViewSet(CustomModelViewSet):
     serializer_class = MtaskSerializer
     filterset_class = MtaskFilter
     select_related_fields = ['material_in', 'material_out', 'mgroup']
-    prefetch_related_fields = ['mlog_mtask']
+    prefetch_related_fields = ['mlog_mtask', 'b_mtask']
     ordering_fields = ['start_date', 'mgroup__process__sort', 'create_time']
     ordering = ['-start_date', 'mgroup__process__sort', '-create_time']