第一步：DataGrid新增LoadingRow="ApplicationRunLogDataGrid_LoadingRow"

<DataGrid x:Name="ApplicationRunLogDataGrid" AutoGenerateColumns="False"
                        CanUserAddRows="False" FontSize="10px"
                        materialDesign:ScrollBarAssist.ThumbCornerRadius="4"
                        d:ItemsSource="{d:SampleData ItemCount=10}" 
                        LoadingRow="ApplicationRunLogDataGrid_LoadingRow">
                    <DataGrid.Columns>
                        <!--<DataGridCheckBoxColumn Header="選中" IsReadOnly="True" Width="60"
                                            Binding="{Binding Checked}"/>-->
                        <DataGridTextColumn Header="序號" IsReadOnly="True" Width="Auto"
                                    Binding="{Binding Header, RelativeSource={RelativeSource AncestorType={x:Type DataGridRow}, Mode=FindAncestor}}" />
                        <DataGridTextColumn Header="SFC名字" IsReadOnly="True" MinWidth="200" Width="Auto"
                                    Binding="{Binding SFCName}"/>
                    </DataGrid.Columns>
                </DataGrid>
 

第二步：

        /// <summary>
        /// 自增序號列
        /// </summary>
        private void ApplicationRunLogDataGrid_LoadingRow(object sender, DataGridRowEventArgs e)
        {
            e.Row.Header = e.Row.GetIndex() + 1;
        }