diff --git a/soong_workflow/models/soong_workflow_mixin.py b/soong_workflow/models/soong_workflow_mixin.py
index 79ab64c87..522e6ab86 100644
--- a/soong_workflow/models/soong_workflow_mixin.py
+++ b/soong_workflow/models/soong_workflow_mixin.py
@@ -1437,7 +1437,10 @@ class SoongWorkflowMixin(models.AbstractModel):
                             id_el = etree.Element("field")
                             id_el.set("name", "log_ids")
                             id_el.set("invisible", "1")
-                            if readonly_arr:
+                            if self._name == "purchase.order":
+                                # 采购订单模型：不添加 is_modify 条件
+                                field_inst.set("readonly", "state in %s" % readonly_arr)
+                            else:
                                 field_inst.set("readonly", "(state in %s) and (is_modify != True)" % readonly_arr)
                     # if required_arr:
                     #     field_inst.set("required", "state in %s" % required_arr)