The polarization sensitivity of the radiative transfer link will affect the accuracy and subsequent application of the remote sensing data of the medium resolution spectral imager (MERSI), so it is necessary to invert, analyze, and quantitatively remove the polarization sensitivity to improve the accuracy of radiometric calibration. Aiming at the MERSI in orbit, the region with large polarization degree of ocean scene is selected. Through the preprocessing of satellite observation data and environmental data, the sea surface radiation state is described based on the probability density model of ocean surface three\dimensional wave slope and Fresnel reflection law. 6SV radiative transfer simulation tool is used to analyze the influence of atmosphere on polarized radiation state. By coupling it with the sea surface radiation state, the atmospheric top polarized radiation state can be obtained, and the inversion of the polarized radiation characteristics of MERSI can be realized. The polarization radiation characteristics of MERSI in specific wave band are analyzed experimentally, and it is found that the polarization degree of MERSI is asymmetrically distributed with the change of satellite zenith angle, and the reflectivity error is stable with the change of satellite zenith angle and polarization degree. The variation law of polarization sensitivity of MERSI under different observation geometry and wind direction is analyzed.