给你一个例子:
procedure TForm1.DBGrid1DrawColumnCell(Sender: TObject; const Rect:TRect;DataCol: Integer; Column: TColumn; State: TGridDrawState);
begin
    if Table1.FieldByName('Population').AsInteger > 20000000 then
        DBGrid1.Canvas.Font.Color := clBlue;    DBGrid1.DefaultDrawColumnCell(Rect, DataCol, Column, State);
end;