Abstract: Coaxial three-mirror optical system is a popular optical system design form in space optical remote sensor. Taking the alignment of high-resolution camera of the GF-1 sensing satellite as an example, the computer-aided alignment technology of coaxial three-mirror optical system was researched. The primary mirror optical axis was set as the benchmark. By adjusting the alignment methods of three-mirror control system field of view and secondary mirror control system aberration, the changes in the relationship between the misalignment rate of secondary mirror and three-mirror and Zernike coefficient were analyzed. The system sensitivity matrix was obtained by the optical design software to guide the system alignment, which improved the accuracy of alignment and shortened the period of alignment. Test results show that the Zernike coefficient of each field of view in optical system is better than 0.05λ, and the RMS value of system wave aberration is better than 0.06 λ. The system passes the on-orbit imaging test with clear and multilayer images.