diff --git a/mongo-plus-core/src/main/java/com/mongoplus/mapping/SimpleTypeHolder.java b/mongo-plus-core/src/main/java/com/mongoplus/mapping/SimpleTypeHolder.java
index 8d97c7e0c233f0c2db6229ae5444239969ddd57c..68874bbccbbdf025a48bcd939fe3031165471cc0 100644
--- a/mongo-plus-core/src/main/java/com/mongoplus/mapping/SimpleTypeHolder.java
+++ b/mongo-plus-core/src/main/java/com/mongoplus/mapping/SimpleTypeHolder.java
@@ -51,6 +51,7 @@ public class SimpleTypeHolder {
         defaults.add(Enum.class);
         defaults.add(BigDecimal.class);
         defaults.add(BigInteger.class);
+        defaults.add(ObjectId.class);
         DEFAULTS = Collections.unmodifiableSet(defaults);
     }