看起来是timeout.
NetTcpBinding有几个timeout,你可以选择适当的一个或者全部都设置.
CloseTimeout 
OpenTimeout 
ReceiveTimeout 
SendTimeout 

另外搜到一篇文章,看看是不是对你有用.
http://www.cnblogs.com/shanyou/archive/2008/09/22/1296061.html

WCF........学习了。。。。。暂时没有发言权。。。。

不懂，学习一下

友情UP
参考一下，也不知道有无帮助
http://www.cnblogs.com/sf4651896/

问题找到了.
是MaxItemsInObjectGraph用了默认大小

感谢大家的帮助.
主要是我没用XML配置WCF.全用代码写的.

MaxItemsInObjectGraph用程序写还比较麻烦
用Attribute设置,把代码贴出来供大家参考下吧
public class CustomDataAttribute : Attribute, IOperationBehavior
    {
        private bool _preserveReferences = false;
        private int _maxItemsInObjectGraph = 65536;

        public CustomDataAttribute(bool preserveReferences, int maxItemsInObjectGraph)
        {
            _preserveReferences = preserveReferences;
            _maxItemsInObjectGraph = maxItemsInObjectGraph;
        }

        public void AddBindingParameters(OperationDescription description, BindingParameterCollection parameters)
        { }

        public void ApplyClientBehavior(OperationDescription description, ClientOperation proxy)
        {
            IOperationBehavior innerBehavior = new CustomDataOperationBehavior(description, _preserveReferences, _maxItemsInObjectGraph);
            innerBehavior.ApplyClientBehavior(description, proxy);
        }

        public void ApplyDispatchBehavior(OperationDescription description, DispatchOperation dispatch)
        {
            IOperationBehavior innerBehavior = new CustomDataOperationBehavior(description, _preserveReferences, _maxItemsInObjectGraph);
            innerBehavior.ApplyDispatchBehavior(description, dispatch);
        }

        public void Validate(OperationDescription description)
        { }
    }

    public class CustomDataOperationBehavior : DataContractSerializerOperationBehavior
    {
        private bool _preserveReferences = false;
        private int _maxItemsInObjectGraph = 65536;

        public CustomDataOperationBehavior(OperationDescription operationDescription, bool preserveReferences, int maxItemsInObjectGraph)
            : base(operationDescription)
        {
            _preserveReferences = preserveReferences;
            _maxItemsInObjectGraph = maxItemsInObjectGraph;
        }

        public override XmlObjectSerializer CreateSerializer(Type type, string name, string ns, IList<Type> knownTypes)
        {
            return new DataContractSerializer(type, name, ns, knownTypes, this.MaxItemsInObjectGraph, this.IgnoreExtensionDataObject, _preserveReferences, this.DataContractSurrogate);
        }

        public override XmlObjectSerializer CreateSerializer(Type type, XmlDictionaryString name, XmlDictionaryString ns, IList<Type> knownTypes)
        {
            return new DataContractSerializer(type, name, ns, knownTypes, _maxItemsInObjectGraph, this.IgnoreExtensionDataObject, _preserveReferences, this.DataContractSurrogate);
        }
    }