public Form1()
    {
        InitializeComponent();
        this.dataGridView1.CellPainting += new DataGridViewCellPaintingEventHandler(dataGridView1_CellPainting);
    }

    void dataGridView1_CellPainting(object sender, DataGridViewCellPaintingEventArgs e)
    {
        if (e.RowIndex == -1)
        {
            bool mouseOver = e.CellBounds.Contains(dataGridView1.PointToClient(Cursor.Position));
            LinearGradientBrush brush = new LinearGradientBrush(
                e.CellBounds,
                mouseOver ?  Color.PeachPuff : Color.LightGray,
                Color.DarkOrange, 
                LinearGradientMode.Vertical);

            using(brush)
            {
                e.Graphics.FillRectangle( brush, e.CellBounds);
                Rectangle border = e.CellBounds;
                border.Width -= 1;
                e.Graphics.DrawRectangle( Pens.Gray, border);
            }

            e.PaintContent(e.CellBounds);
            e.Handled = true;
        }
    }

------解决方案--------------------
唯一的可能性，你有隐藏列