diff --git a/library/think/Model.php b/library/think/Model.php
index 42c08410..ebeffbb4 100644
--- a/library/think/Model.php
+++ b/library/think/Model.php
@@ -1081,7 +1081,7 @@ abstract class Model implements \JsonSerializable, \ArrayAccess
 
         // 删除条件
         $pk = $this->getPk();
-        if (isset($this->data[$pk])) {
+        if (is_string($pk) && isset($this->data[$pk])) {
             $where = [$pk => $this->data[$pk]];
         } elseif (!empty($this->updateWhere)) {
             $where = $this->updateWhere;