Abstract: As a typical double-faulted lacustrine basin, the Gubei sag is affected by the alternation of faults along the boundary. The internal structure of the lacustrine basin is unique, the source system is complex, and the deposition types are diverse. Therefore, the accurate evolution restoration of the sedimentary system is the key to guiding oil and gas exploration in this type of basin. In this paper, the core, thin section, logging and seismic data were comprehensively used to conduct a detailed study on the characteristics of the source and sedimentary facies distribution of the third member of Shahejie formation in Gubei sag. The results showed that the alternating activities of Changdi fault and Chengdong fault in the east and west sides of Gubei sag resulted in the geomorphic features of “one swell sandwiched by two sags” of the lake basin. The strong activity of Zhuangnan fault in the north caused the characteristic of “faulting in the north and overlapping in the south” in the eastern subsag. The interior of the lacustrine basin is mainly controlled by the provenances coming from the 4 directions of Chengdong, Changdi, Gudao and Gudong. Progradational fan delta and retrogradational subaqueous fan distributed on the Chengnan steep slope accumulated alternatively and vertically. Progradational fan deltas are distributed in the faulted belt of Changdi steep slope and deltas are distributed on the eastern and western gentle slopes of Gubei sag. The fan delta coming from Gudong swell extends from the southeast to the north in the sag. Generally, faults give a few impacts on the gentle slope where fan delta sediments are mainly found and controlled by lake level and ancient landform. The steep slope is mainly constrained by both fault activity and lake level, and is dominated by subaqueous fan, fan delta and slip turbidite fan