diff --git a/library/think/db/Query.php b/library/think/db/Query.php
index dcf735b9..8dcfcfa0 100644
--- a/library/think/db/Query.php
+++ b/library/think/db/Query.php
@@ -747,9 +747,9 @@ class Query
         }
 
         if (isset($this->options['field'])) {
-            $field = $this->options['field'] + $field;
+            $field = array_merge($this->options['field'], $field);
         }
-        $this->options['field'] = $field;
+        $this->options['field'] = array_unique($field);
         return $this;
     }