Multiple marginal subsags in the northern South China Sea Basin have been confirmed as subsags with rich hydrocarbon，but unclear favorable reservoir controlling factors have hindered their efficient development. By taking the Paleogene deep reservoir（Wenchang Formation and Enping Formation）in the northern area of Huizhou Sag（the northern Huizhou Sag）in the Pearl River Mouth Basin as an example，the reservoir characteristics and controlling factors were analyzed by using the data of drilling，logging，casting thin section，scanning electron microscopy，and physical property analysis. The results show that there are obvious differences in reservoir characteristics between the eastern and western areas of the northern Huizhou Sag. The rock types of the east area are mainly lithic sandstone and feldspar lithic sandstone，and the favorable reservoir space is mainly secondary solution pores. The reservoir rock types in the western area are lithic feldspar sandstone and feldspar quartz sandstone，and the fa‐vorable reservoir space is mainly residual primary pores. The eastern area is dominated by reservoirs with low porosity，medium porosity，and low and ultra-low permeability，while the western area is dominated by reservoirs with low porosity and low and ultra-low permeability. It is affected by the variability of faults and the spatiotemporal evolution of source-sink systems，and the differences in reservoir parent material，reservoir maturity，and diagenesis are significant. In the eastern area，proximal transport occurs. The sediments are rich in feldspar，and the coupling of hydrocarbon generation and acid discharge with the fracture system in the later stage leads to large-scale dissolution and the development of secondary solution pores. The transfer belt in the western area has a strong sand transport capacity and high rigid minerals，which effectively slows down compaction and facilitates the retention of primary pores. Early oil and gas charging and overpressure can also improve the reservoir’s physical properties.Finally，two high-quality reservoir development models，“primary porosity”and“solution porosity”，are established.