Cloud top pressure can be used to estimate cloud height, which is important for meteorological observation and cloud characteristics research. Based on 763 nm and 765 nm bands (in oxygen A-band) of the Directional Polarimetric Camera (DPC) onboard GF-5 satellite, a cloud top pressure retrieval method is studied. First, the calculation formula of atmospheric pressure is obtained by using radiative transfer simulation and polynomial fitting, and the fitting error of the formula is analyzed and corrected. Then, the influence of aerosol, atmosphere profile and other factors on the cloud top retrieval is analyzed, and the stability test and principle verification of the retrieval method are further carried out by using clear-sky surface. The stability test results show that the oxygen A-band retrieval method is stable and can be applied to different weather conditions and view angles, and the principle verification results show that the DPC retrieved pressure is in good correlation with the DEM estimated pressure, with the average deviation of surface pressure of 47.6 hPa. Finally, the retrieved DPC cloud top pressure is compared with the MODIS cloud top pressure product (MYD06), and it is shown that cloud top pressure observation results of the two satellitesare in good agreement.