利用委托在子窗体设置父窗体控件

子窗体中

public delegate void ChangeGYSHandler(DataTable tb,string mpsn);  //定义委托

 public event ChangeGYSHandler ChangeGYS;  //定义事件

 ChangeGYS(ds_new1.Tables[0], dataGridView1.Rows[e.RowIndex].Cells[0].Value.ToString()); 

父窗体

 Form2 f2 = new Form2();
                    f2.ChangeGYS += new ChangeGYSHandler(Change_GYS);//将事件和处理方法绑在一起，这句话必须放在f2.ShowDialog();前面
                    f2.cpsn = cpsn;
                    f2.ShowDialog();  

  public void Change_GYS(DataTable tb,string mpsn)
        {
            combobox_gys.DataSource = tb;
            combobox_gys.DisplayMember = "SupplierFName";
            combobox_gys.ValueMember = "FSupplyID";


            textBox_mpsn.Text = mpsn;
        }