The Directional Polarization Camera (DPC) is a Chinese Earth observation satellite sensor carried on Gaofen-5B satellite, which has observation capacity of multi-angle, multi-spectral, and polarization. Due to its wide field of view (±50°) and short revisit period (2 days), the DPC is capable of monitoring global changes in aerosol optical depth (AOD). In this paper, we develop a DPC AOD retrieval algorithm over open ocean waters based on the black pixel assumption in the near-infrared band, namely at 865 nm. The optimization of the retrieval process is achieved by matching the multi-angle measured reflectance with the reflectance from the radiative transfer simulation. First, based on the so-called Ocean Successive Orders with Atmosphere—Advanced (OSOAA) radiative transfer model, the AOD lookup table is constructed by storing the simulated reflectance at the top of atmosphere (TOA) corresponding to various AODs. Then, the satellite’s observation geometry is used to interpolate the simulated reflectance. The retrieval scheme of this method is to minimize the residuals between the measured directional data and the simulated data in each direction. Specifically, a second-order polynomial is used to fit the cost function for each observation geometry based on the least squares method. By solving this polynomial, a set of AOD values for the pixel is obtained, and the median of this set is taken as the final AOD. Finally, we validate the effectiveness of the proposed algorithm by conducting a pixel-by-pixel comparison of the retrieval results of the DPC and the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Terra satellite. The results show that the spatial distribution of DPC AOD is consistent with that of MODIS, with a coefficient correlation of determination (R2) of 0.726 and a root mean square error (RMSE) of 0.01. The results indicate that the proposed algorithm can provide effective technical support for AOD inversion of DPC over open ocean.