<Grid>

    <DataGrid Name="datagrid1" Margin="123,146,553,42" AutoGenerateColumns="False" Height="131" Width="244">

        <DataGrid.Columns>

            <DataGridTextColumn Header="姓名" Width="105" Binding="{Binding Path=Name}" />

            <DataGridTextColumn Header="年龄" Binding="{Binding Path=Age}" />

            <DataGridComboBoxColumn x:Name="dataGridComboBoxColumn1"  SelectedItemBinding="{Binding Path=aaa}" Header="科目" />

        </DataGrid.Columns>

    </DataGrid>

    <Button Content="Button" HorizontalAlignment="Left" Margin="292,102,0,0" VerticalAlignment="Top" Width="75" Click="Button_Click"/>

    <DataGrid x:Name="datagrid2" Margin="429,146,247,42" AutoGenerateColumns="False" Height="131" Width="244">

        <DataGrid.Columns>

            <DataGridTextColumn Header="姓名" Width="105" Binding="{Binding Name}" />

            <DataGridTextColumn Header="年龄" Binding="{Binding Age}" />

            <DataGridComboBoxColumn x:Name="dataGridComboBoxColumn2"  SelectedItemBinding="{Binding aaa}" Header="科目" />

        </DataGrid.Columns>

    </DataGrid>

</Grid>

private void Button_Click(object sender, RoutedEventArgs e)

{

    datagrid1.ColumnWidth = DataGridLength.Auto;

    ObservableCollection<Person> obc = new ObservableCollection<Person>();

    obc.Add(new Person() { Name = "张三", Age = 43, Address = "上海", aaa = "语文" });

    obc.Add(new Person() { Name = "李四", Age = 42, Address = "北京", aaa = "数学" });

    obc.Add(new Person() { Name = "王二女", Age = 50, Address = "美国", aaa = "化学" });