AISM telescope is the abbreviation of Accurate Infrared Magnetic System. This telescope is the first mid infrared system internationally used for observing the solar magnetic field. The system is an off-Axis telescope with an aperture of 1 meter. The optical path is complex and the light is folded over a long distance through multiple flat and aspheric mirrors and coupled with mechanical rotation axis. The conventional alignment methods cannot be applied. This paper describes the methods for reserving assembly reference for each module and the system optical axis consistency adjustment method. The method has been verified through actual experiment and can achieve high precision. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.