我找到了两种方式添加行,在MSDN找到了设置默认值的方法,但是我做了断点发现,当我添加行时,并没有进入dataGridView1_DefaultValuesNeeded方法
 private void dataGridView1_UserAddedRow(object sender, DataGridViewRowEventArgs e)
        {
          //  MessageBox.Show("","");
        }        private void button9_Click(object sender, EventArgs e)
        {
             DataGridViewRow row = new DataGridViewRow();
             dataGridView1.Rows.Add(row);
        }
        
        private void dataGridView1_DefaultValuesNeeded(object sender,System.Windows.Forms.DataGridViewRowEventArgs e)
        {
            e.Row.Cells["MoOrder"].Value = "新添加";
        }