Because the high-precision detection of large-aperture plane mirror surface shape is a process of precise adjustment, the surface shape recovery accuracy is easily disturbed by human subjective factors in the detection process. In order to solve the problem of high-precision surface shape detection of large-aperture plane mirrors, the eccentricity error of optical path detection and the resulting change in the calculation accuracy of the ritchey angle, the distance from the center of the interferometer to the plane mirror and other linkage errors are analyzed. By using optical software to build a 2 m plane mirror detection model, set different eccentricity errors to obtain the system wave aberration, solve the system wave aberration data to obtain the plane mirror shape data to be measured, and compare it with the preset standard surface shape. The analysis shows that the surface shape recovery result is more sensitive to the eccentricity error. It is necessary to ensure that the difference between the two ritchey angles is within the range of 12°~25°, and the eccentricity error is controlled within 5% of the diameter during detection. It is not sensitive to the eccentricity error and the change of linkage error caused by it, and the RMS accuracy of the surface to be measured is within 10-3λ. Based on the above error simulation analysis, the actual φ2 m plane mirror surface shape detection is guided, and the results show that the RMS of the plane mirror reaches 0.020 9 λ, and the PV is 0.128 4 λ (λ=632.8 nm). The purpose of this paper is to reveal the degree of influence of eccentricity error and linkage error on the shape of a 2 m plane mirror, which has a guiding role in the construction of the actual optical path of the large-aperture mirror plane mirror and the reduction of artificial adjustment errors.