Polarization detection tests are carried out on China's self-developed Scanning Polarimeter (POSP), mainly including on-ground tests and in-flight tests. Among them, the on-ground tests are to scan the sky to obtain the data of polarization degree and radiation luminance of the sky, while the in-flight tests are to scan the earth's surface to obtain the data of polarization degree and radiation luminance of the earth's surface. In order to compare and analyze the data of polarization degree and radiation luminance obtained by POSP, a three-beam simultaneous polarization camera is equipped for polarization detection during polarization detection tests. The results show that the data of polarization degree and radiation luminance obtained by the two polarization instruments have good consistency, and the validity of the data obtained by POSP in polarization detection tests is preliminarily verified, which can provide an effective basis for the inversion of atmospheric aerosol parameters in the later stage.