The article proposes a shear calibration method for a transverse shear interferometry (LSI) wavefront sensor based on the optical layout of a point light source microscope (PSM). A simulation model of four wave LSI was introduced to analyze the influence of window size and shear amount of spatial filters on the accuracy of shear wavefront feature extraction (SWFE) method. The simulation results show that the accuracy of the SWFE method decreases at smaller shear rates. The proposed calibration method utilizes the optical layout of PSM to generate spot images of point sources on the detector plane of the sensor itself. The shear amount is calibrated by the relationship between the lateral distance of the spot image and the diffraction order distribution of the grating. In the experiment, this method was used to calibrate the SID4 wavefront sensor and the Hartmann mask LSI wavefront sensor with improved circular aperture. A patterned phase plate was produced as a sample. Adopting etching depth features of two wavefront sensors and comparing them with commercial ZYGO ® The test results of the interferometer were compared. Verified the feasibility and accuracy of the proposed calibration method. This calibration method provides a convenient way to calibrate the shear amount of LSI wavefront sensors with high precision.