In order to characterize the distribution of calcareous interlayers and provide a basis for fine tapping of remaining oil in the later stage of oilfield development. Based on the drilling coring and logging data of Panyu oilfield in the Pearl River Mouth Basin of the South China Sea in the study area, and through the analysis of the lithology, logging curves, thin sections and other characteristics of the calcium interlayers, the genesis and identification features of the calcium interlayers in the Pearl River Formation in the study area were determined. It is concluded that the Pearl River Formation in Panyu oilfield is dominated by delta front deposits, and the calcareous interlayer has the characteristics of dense cementation, thin thickness, poor physical properties, and discontinuous distribution. Its formation is mainly related to the supersaturated precipitation of calcium bearing fluid in the diagenetic stage. Calcium interlayers are divided into two types based on their developmental position: apical calcium and intralayer calcium. The top calcium is mainly controlled by sequence boundaries and has strong continuity. The intra layer calcium is controlled by sedimentary microfacies and has poor continuity. Calcareous interlayers mainly develop at the bottom of underwater distributary channel sand bodies and the top of river mouth dam sand bodies, and their distribution range and scale are controlled by the sedimentary microfacies and sand body stacking interface. The distribution of calcareous interlayers is closely related to the potential of remaining oil, and the continuous development of calcareous interlayers provides favorable conditions for the economic potential of large bottom water, low oil column, and heavy oil reservoirs.