using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace SLWebService.Web
{
    public class Person
    {
        public string Name { get; set; }
        public int   Age { get; set; }
    }
}

Code
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Services;

namespace SLWebService.Web
{
    /// <summary>
    /// MySLWebService 的摘要说明
    /// </summary>
    [WebService(Namespace = "http://tempuri.org/")]
    [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
    [System.ComponentModel.ToolboxItem(false)]
    // 若要允许使用 ASP.NET AJAX 从脚本中调用此 Web 服务，请取消对下行的注释。
    // [System.Web.Script.Services.ScriptService]
    public class MySLWebService : System.Web.Services.WebService
    {

[WebMethod]
        public string HelloWorld()
        {
            return "Hello World";
        }

[WebMethod]
        public Person[] GetPeople()
        {
            List<Person> People = new List<Person>()
        {
           new Person{ Name="Jack",Age=12},
           new Person{ Name="Tom",Age=22},
           new Person{ Name="Simon",Age=32},
           new Person{ Name="Richard",Age=26}
        };

return People.ToArray();
        }
        
    }
}

<UserControl x:Class="SLWebService.Page"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
    Width="400" Height="300">
  <StackPanel Width="400" Height="300" Background="Wheat">
         <TextBlock Text="通过WebService取得的数据如下" TextAlignment="Center" Foreground="Red"  FontSize="18"></TextBlock>
         <Button x:Name="btnGetWebService" Width="200" Height="30" Content="获取数据" Click="btnGetWebService_Click"></Button>
        <ListBox x:Name="People" Width="300" Height="200" Margin="20">
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <StackPanel Orientation="Vertical">
                        <StackPanel Orientation="Horizontal">
                          <TextBlock Text="姓名" Width="100" Foreground="Blue" ></TextBlock>
                          <TextBlock Text="年龄" Width="100" Foreground="DarkBlue"></TextBlock>
                        </StackPanel>
                        <StackPanel Orientation="Horizontal">
                        <TextBlock Text="{Binding Name}" Foreground="Red"  Width="100" ></TextBlock>
                        <TextBlock Text="{Binding Age}"  Foreground="Green"  Width="100" ></TextBlock>
                        </StackPanel>
                    </StackPanel>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>
    </StackPanel>
</UserControl>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;

using SLWebService.MyWebServiceRef; //加入对MyWebServiceRef的引用

namespace SLWebService
{
    public partial class Page : UserControl
    {
        public Page()
        {
            InitializeComponent();
        }

private void btnGetWebService_Click(object sender, RoutedEventArgs e)
        {
            //使用WebService从服务器端得到数据并在本地端进行处理
            MySLWebServiceSoapClient client = new MySLWebServiceSoapClient();   
            client.GetPeopleCompleted  += new EventHandler<GetPeopleCompletedEventArgs>(client_GetPeopleCompleted);
            
            client.GetPeopleAsync();
        }

void client_GetPeopleCompleted(object sender, GetPeopleCompletedEventArgs e)
        {
            if (e.Error == null)
            {
                People.ItemsSource = e.Result; //绑定结果到UI的List控件
            }
        }

}
}