Now the abroad commercial interferometer ZYGO can provide some surface form evaluation coefficients based on ISO10110-5, which the domestic interferometers don’t have. These surface form evaluation coefficients can be actualized by the method of wavefront decomposition. Firstly the Zernike polynomial coefficients are achieved by Gram-Schmidt least square method, secondly different surface forms are subtracted from the original wavefront which contains the tested information, and thus the quantitative analysis of these coefficients is realized. Contrast with the output from ZYGO, the validity of the data from the self-compiled code is tested. And the interference patterns from the wavefront decomposition are also helpful to the optical processors to analyze the errors and the application result.