In the assembly of space camera, the assembly of large aperture mirror is the key of the system assembly. In this paper, the flexible supported mirror of space camera is taken as the research object, and a process route is proposed to complete the micro-stress assembly of the mirror and the transmission from optical datum to mechanical datum at one time by taking the adhesive assembly of the mirror and the transmission from optical datum to mechanical datum into consideration. According to this process route, the assembly process design and installation platform construction are completed. In addition, the factors affecting the micro-stress assembly of the mirror are analyzed theoretically and experimentally, and the transfer accuracy of the optical-mechanical reference is analyzed. This process method has been successfully applied to the assembly of a space camera's primary mirror. After the assembly, the shape of the primary mirror RMS is less than λ/50, and the Angle between the optical axis and the normal of the structure's mounting surface is less than 10". The process method presented in this paper provides a technical reference for the assembly of similar optical-mechanical systems. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.