方法一：

private void dataGridView1_RowPrePaint(object sender, DataGridViewRowPrePaintEventArgs e)
{
DataGridViewRow dgr = dataGridView1.Rows[e.RowIndex]; 
try
{
if (dgr.Cells["onduty1"].Value.ToString() == "" || dgr.Cells["onduty1"].Value.ToString() == null)
{
dgr.Cells["onduty1"].Style.BackColor = Color.Red;
}
 
}
catch (Exception ex)
{

 MessageBox.Show(ex.Message); 
}
}

 

方法二：

dataGridView1.Rows[index].Cells["測試結果"].Style.BackColor = Color.White;