Abstract: Diaobei sag in the East China Sea shelf basin is characterized by a complex fault systems and multiple fault configurations, and there is little research on the whole fault system and its evolution. The distribution and evolution characteristics of faults in this area were systematically studied based on 2D seismic data, and the fault evolution model in Diaobei sag was discussed in this paper. The results show that the fault system can be grouped vertically into three fault systems, that is the lower(extensional), the middle(compressional), and the upper(extensional shear)fault systems, with the bottom of Oligocene Huagang Formation and the bottom of Upper Miocene Santana Formation as the boundaries. The fault configuration of the lower extensional fault system mainly include single fault type, same-directim stepover, composite horst stepover and other fault combination, which mainly formed in the rifting and say stage of the depression, and the faults controlled the development of sedimentary strata. The fault configurations of the middle compressional fault system are mainly Y-shaped, anti-Y-shaped and negative flower-shaped, and they mainly formed in the say and subsidence inversion stage of the sag. The strata have obvious characteristics of upper arch. The fault configurations of upper extensional fault system are mainly interlayer faults, with the banded and echelon distribution on plane. The fault formed in the subsidence stage of the sag, and its control of the formation is weak. Diaobei sag can be divided into western slope zone, central deep depression zone and eastern fault terrace zone according to fault styles and characteristics. From the perspective of fault evolution stages, the fault systems of Diaobei sag can be diveded into fault depression-say system, fault say-subsidence inversion system, and the regional subsidence system. This research could provide references for the petroleum exploration, exploitation and geology research.