The polarization calibration of an airborne multi-angle polarimetric radiometer was researched to eliminate the polarization effects induced by itself and to improve its measurement accuracy. First, instrument detection equations with calibration coefficients were derived according to the main factors that have been induced into the instrumental polarization effects, and the expression of calibration coefficients was solved based on the detection equations for the same signal when the instrument was fixed at states of 0°and 90°.Then, the calibration method to get the signals of the two instrument states and to solve the calibration coefficients were designed. Finally, the polarization calibration coefficients were computed from the measured data using a non-polarized light source and a completely linearly polarized one, respectively, and the polarized calibration results were verified by adjusting the polarization degree of the incident light. The results indicate that the instrument can offer a polarized measurement accuracy better than 0.5%, which meets the requirements of the instrument polarimetry.