Abstract: The Chinese GF-5 satellite was launched successfully in May 2018, which was equipped with a directional polarization camera (DPC). The DPC sensor's radiometric characterization may be affected by many factors, such as the vibration during launch, the outgassing when instrument leaves atmosphere, the ageing of the optics and circuit system, resulting in a certain deviation between the in-flight performance and the preflight radiometric calibration. Based on the in-flight calibration method for polarization measurements of DPC, using the sunlight reflected within the sun's glitter over ocean, the DPC measurements were adopted during its commissioning phase. The preliminary result shows that the measured degree of linear polarization values are consistent with the theoretically values, with small average deviations of $-$0.03, $-$0.04, $-$0.01 for 490, 670, 865 nm bands, respectively. It indicates that the DPC's polarimetric characterization have not been changed significantly after launch. This method is based on natural target, and it can be used to monitor the temporal polarimetric sensitivity of DPC.