In order to reduce the difficulties in manufacture and assembly of the spatial filter with two square windows in image plane, we propose a grating lateral shearing interferometry based on a nine step phase shifting method, which is used to calibrate the zero-order phase error. The zero-order crosstalk could be eliminated only by a variable space filter. The parameters are designed and the principle verification system is completed for a projection lithography lens with numerical aperture of 0.125. Then the wavefront aberration measurement of this lens is achieved by the restoration of shearing phase and the reconstruction of wavefront. The results show that the wavefront aberration is less than 20.32 nm. The repeatability precision of the grating lateral shearing interferometer is measured. The root-mean-square value of the repeatability precision is 0.1303 nm, which shows the performance of this system is well.