DataGridView中的列类型设置为Combo，模式为可以选择&可以输入，解决方法。

private void DgvLayerPringSetting_EditingControlShowing(object sender,DataGridViewEditingControlShowingEventArgs e)
        {
            var cb = e.Control as ComboBox;
            
            if (cb != null)
            {
                cb.MaxLength = 2;
                cb.DropDownStyle = ComboBoxStyle.DropDown;
                cb.AutoCompleteMode = AutoCompleteMode.Suggest;
                cb.AutoCompleteSource = AutoCompleteSource.ListItems;
            }
        }