我以前做了一个绑定下拉框的代码，不知道对你现在这个问题是否有帮助。代码贴出来你看看

前台设置：

<ComboBox x:Name="chbBox" Margin="5,5,0,5" VerticalAlignment="Center" Width="80">
<StackPanel x:Name="spList" Orientation="Vertical" ScrollViewer.HorizontalScrollBarVisibility="Hidden" ScrollViewer.VerticalScrollBarVisibility="Visible"></StackPanel>
</ComboBox>

后台绑定：

ServiceProxy.SrKpipCxyhServiceProxy objProxys = new SrKpipCxyhServiceProxy();
objProxys.ReadAllCxyhs(LoadAllCxyhs);

private void LoadAllCxyhs(List<object> cxyhjs)
{
List<Cxyh> YhJs = new List<Cxyh>();
foreach (object o in cxyhjs)
{
YhJs.Add(o as Cxyh);
}

//去重复
var queryYhJs = from v in YhJs
select v.Fz;//查分组
var name = queryYhJs.Distinct();//去重复
foreach (var item in name)
{
CheckBox chk = new CheckBox();
chk.Content = item;
chk.Tag = item;
spList.Children.Add(chk);
}
}