Alignment errors of sub-aperture gratings in the optical design of tiled gratings and tiled grating compressors are almost unavoidable. It is important to study the relation between alignment errors and temporal properties of the tiled graing. Analyzed by pulse compression theory, the relation between these alignment errors and focused pulse width broadening is obtained. And the numerical calculation results show that planar alignment errors have much more important influences on the pulse duration, which must be controlled within 21.08 μrad, and the groove-width difference also affects the pulse duration severely, so the ratio between the groove-width difference and groove-width must be controlled within 10-5. From the point of view of eliminating angular dispersion, the planar tilt errors and groove parallelism can ompensate each other, and the groove-width difference and planar errors of tip can also compensate each other.