According to the simulation results of cloud polarization radiative transfer， the water cloud with polarization rainbow characteristics is selected as the experimental target to test the space environment adaptability of key polarization parameters. On the basis of the characteristics of polarization imager directional polarimetric camera， the large area water cloud is identified by cloud phase state. The relative transmittance and polarizability parameters are verified according to the polarization radiation model of the instrument by using the measurement data of different polarizing directions of water cloud. The experimental results show that the change of relative transmittance is less than 0.2%， the variation of polarizing degree for optical lens is less than 0.01， and the instrument state is stable. At the same time， the ability of polarization imager to identify cloud phase state by cloud polarization characteristics is verified. The methods and test results provide reference for on orbit detection and calibration of polarization imager， and provide basis for inversion of cloud products using multi angle polarization data.