Abstract: The main object of this paper is precise alignment and inspection process technology for reflecting collimator with focus length of 4 000 mm and aperture diameter of 400 mm. As the detection and calibration datum of a certain type of optical system, this reflecting collimator has a very high demand in system imaging quality, resolution and beam parallel difference. Therefore, this paper focuses on key processes such as micro-stress bonding method, spacing precise adjustment method, optical axis consistency adjustment method of primary and secondary mirror of the Cassegrain system. Then precise alignment and inspection is carried out with optical self-collimation method. Final system resolution of reflecting collimator is better than or equal to 0.8 second, the parallel deviation is better than or equal to 3 seconds, star energy is concentrated without obvious aberration, and vertical line of cross-graduation could be perpendicular to the base plane.Results show that optical self-collimation method used in reflecting collimator can meet design requirements.