For the parallel plate lateral shearing interferometer,if there is an angle error between the parallel plates in the two directions,the shearing interferograms of two directions are not ort hogonal,accuracy of wavefront measurement will be worsened.In order to analyze the influence of the angle err or between the parallel plates on the accuracy of the wavefront measurement,accuracy of wavefront reconstruction is s tudied through simulation experiments,and the relationships among the fitting accuracy of Zernike polynom ial coefficients,the root mean square (RMS) and root mean square error (RMSE) of the reconstructed wavefront an d the angle error of the parallel plate are analyzed.The relationships of the RMS and RMSE of the reconstructed w avefront and the shear are analyzed when the angle error is constant.It is shown that the angle error betw een two parallel plates should be reduced to improve the accuracy of wavefront reconstruction,more Zernike polyno mials should be used to fit the wavefront,and the ratio of shear to wavefront size should be greater than 10%.T he conclusions of this paper will play a guiding role in the installation and adjustment of the parallel plate lat eral shearing interferometer.