The polarization scanner (POSP) is a remote sensor which can simultaneously measure polarization and aperture. The optical-mechanical system design and index requirements of POSP are introduced. In order to ensure the measurement accuracy, the environmental adaptability design and analysis of POSP are carried out aiming at the mechanical property during the transport and launch phases and the thermal environment of in-orbit operation, and the thermal vacuum and identification level mechanical tests are carried out. The experimental results show that the fundamental frequency of the instrument is about 110 Hz, and the modes are basically consistent with the simulation results. The strength and hardness of the whole machine meet requirements. After the thermal vacuum test, the output of the instrument is normal, and each component of the optical-mechanical system works normally. The performance of the whole machine is tested before and after the thermal and mechanical tests. The results show that the coincidence degree of field of view is more than 90%, and the polarization precision is better than 0.5%. The instrument has good adaptability to the space environment, and meets the stable and reliable work requirements on the ground and in orbit.