Theeffect of the moving mirror tilt errors on the modulation depth wasanalyzed for the circular aperture in Michelson interferometer. To meet the requirements of interference modulation, the tilt angle of the moving mirror is best controlled within 1″ under the theoretical calculation, corresponding to the phase error within ±6°. In order to solve the key problem, the dynamic alignment system wasused to align the tilt error of the moving mirror ,and make alignment between the moving mirror and the fixed mirror. The experimental results show that the root mean square of phase errors XR and YR is 1.02°and 1.25° respectively by dynamic alignment system to satisfy the systems requirements.It is shown that the dynamic system can effectively align the tilt error of the moving mirror in the longer distance movement process. It is a certain guiding significance to design and develop for the spectrometer with higher resolution.