Equivalent optical path method is used to study the optical path difference，the characteristics of interference fringes of Michelson interferometer by using He-Ne laser source is also analyzed theoretically. It is found that off-center problem of the interference fringes is mainly caused by the no perpendicularity of the two mirrors or the laser and the beam expander. Based on the software of Matlab，a simulation program MIGUI for Michelson interferometer is designed. MIGUI can not only accurately simulate the process of wavelength measurement，but also simply adjust the five parameters affecting interference fringes and study the intensity distribution of fringes quantitatively. Finally，MIGUI is used to study the influence of the position of the moving mirror and the beam expander on the interference fringes. It is found that the change of the position of the moving mirror has a greater effect on the fringe radius than the latter.