The grating tiling technology is one of the most effective means to increase the aperture of the gratings.The linedensity error(LDE)between sub-gratings will degrade the performance of the tiling gratings,high accuracy measurement and compensation of the LDE are of significance to improve the characteristics of the tiled-grating compressor.In this paper,the influence of LDE on the output pulses of the tiled-grating compressor is quantitatively analyzed by means of numerical simulation,the output beams drift and output pulse broadening result from the LDE are presented.Based on the numerical results we propose a compensation method to reduce the degradations of the tiled-grating compressor by applying angular tilt error and longitudinal piston error at the same time.