diff --git a/Falcon.SugarApi/DatabaseDefinitions/SugarConnectionConfig.cs b/Falcon.SugarApi/DatabaseDefinitions/SugarConnectionConfig.cs
index a422a01..dcb8822 100644
--- a/Falcon.SugarApi/DatabaseDefinitions/SugarConnectionConfig.cs
+++ b/Falcon.SugarApi/DatabaseDefinitions/SugarConnectionConfig.cs
@@ -24,15 +24,28 @@ namespace Falcon.SugarApi.DatabaseDefinitions
             this.ConfigureExternalServices ??= new ConfigureExternalServices { };
             //设置Nullable
             this.ConfigureExternalServices.EntityService += (p, c) => {
-                if (p.GetCustomAttribute<RequiredAttribute>() != null) {
-                    c.IsNullable = false;
-                    return;
-                }
                 var pt = p.PropertyType;
+                //所有类型默认可空
+                bool na = true;
+                //字符串默认可空
+                na = pt == typeof(string) ? true : na;
+                //Nullable<>类型可空
                 if (pt.IsGenericType && pt.GetGenericTypeDefinition() == typeof(Nullable<>)) {
-                    c.IsNullable = true;
-                    return;
+                    na = true;
                 }
+                //RequiredAttribute标记不可空
+                if (p.GetCustomAttribute<RequiredAttribute>() != null) {
+                    na = false;
+                }
+                //主键不可以为空
+                if (p.TryGetAttribute<KeyAttribute>(out var _)) {
+                    na = false;
+                }
+                //定义主键不可以为空
+                if (p.TryGetAttribute<SugarColumn>(out var sc) && sc.IsPrimaryKey) {
+                    na = false;
+                }
+                c.IsNullable = na;
                 //var sc = pt.GetCustomAttribute<SugarColumn>();
                 //if (sc != null) {
                 //    c.IsNullable = sc.IsNullable;
diff --git a/Falcon.SugarApi/TypeExtend.cs b/Falcon.SugarApi/TypeExtend.cs
new file mode 100644
index 0000000..0178c11
--- /dev/null
+++ b/Falcon.SugarApi/TypeExtend.cs
@@ -0,0 +1,25 @@
+using System;
+using System.Diagnostics.CodeAnalysis;
+using System.Reflection;
+
+namespace Falcon.SugarApi
+{
+    /// <summary>
+    /// 类型相关扩展
+    /// </summary>
+    public static class TypeExtend
+    {
+
+        /// <summary>
+        /// 尝试获取Attribute
+        /// </summary>
+        /// <typeparam name="T">Attribute类型</typeparam>
+        /// <param name="info">属性</param>
+        /// <param name="p">定义的特性</param>
+        /// <returns>定义返回True，否则False</returns>
+        public static bool TryGetAttribute<T>([NotNull] this PropertyInfo info, out T p) where T : Attribute {
+            p = info.GetCustomAttribute<T>();
+            return p != null;
+        }
+    }
+}