To realize the engineering application of the high frequency and high precision tiling error compensation, a novel method for error compensation of large-aperture tiled-grating compressor was presented by using a small-aperture mirror. The relationship between the amount of mirror compensation and the tiling error was analyzed for two-pass Z-type compressor. The influence of the compensated tiling error on the focus energy was quantitatively compared with the numerical simulations, which was combined with the ray-tracing method and principle of Fraunhofer far field diffraction. The validity was verified and the error tolerances for direct drive and mirror compensation were obtained. The results show that this method can decrease the precision demand significantly for tiled-grating.