属已解决问题。 
      if (gdSelected in State) then
      begin
        DBGrid.Canvas.Brush.Color := clRed;选中为红色
        DBGrid.Canvas.Font.Color := clGreen;字体为绿色
      end
      else
        if (DBGrid.DataSource.DataSet.RecNo mod 2=1) then
          DBGrid.Canvas.Brush.Color:= clYellow;否则奇数行为黄色
        else
          DBGrid.Canvas.Brush.Color:= clBlue;偶数行为蓝色
      DBGrid.DefaultDrawColumnCell(Rect, DataCol, Column, State);