一种方法是在绑定项目之前，你可以将附加项目插入到DataSet绑定中。

尝试这种方式或提供代码示例。

I am using two dropdown list box. dropdown 2 get data from dropdown 1 based on databind. Now i want add one extra value into dropdown list 2...If i am using AppendDataBoundItems="true" mean dropdown list 2 not working properly...so, plz help me to correct this problem...

One way is before bind the item, you can insert the additional item to DataSet bind that.
Try that way or provide your code sample.