Massive satellite constellations are rapidly developing. Space optical payloads now require batch manufacturing. This research aims to break traditional bottlenecks of high costs and long cycles. It focuses on modular design, process optimization, and automated testing for micro-sized space optical payloads. A Maksutov-Cassegrain optical system is developed. It combines a small F-number with tiny pixels. At 500 km orbital height, it achieves 4.5 m ground sample resolution. Its imaging swath is 13.5 km × 13.5 km. The total weight is only 1.1 kg. Modular design allows interchangeability between lenses and focal plane components. Centering assembly technology significantly improves alignment efficiency. Automated assembly and calibration lines complete system integration and focal plane calibration. Overall development efficiency increases by 50%. These results provide key technical support. They help further reduce development time and cost for micro-sized space optical payloads.