Abstract: This study aims to clarify the main controlling factors of hydrocarbon accumulation in Area S in the central Pinghu Structural Belt of Xihu Sag, East China Sea Shelf Basin, improve the hydrocarbon accumulation model of Santan Deep Sag, and provide support for the optimization of favorable exploration zones and field deployment in the study area. Based on available seismic and drilling data of Area S as well as newly acquired data from Well A, the petroleum geological conditions in the study area, including hydrocarbon generation, migration, reservoir physical properties and fault system configuration, are systematically analyzed. Combined with organic geochemical testing data, the hydrocarbon accumulation and evolutionary processes are comprehensively investigated. The results indicate that deep source faults act as the critical migration pathways for hydrocarbons, and reservoir physical properties impose a dominant control on hydrocarbon enrichment. The results further reveal the regional hydrocarbon accumulation regularities and deepen the cognition of the hydrocarbon accumulation model of Santan Deep Sag, which provides a solid theoretical basis for the optimization of prospective exploration zones and future exploration arrangements.