Abstract: According to regional structural geological characteristics and aeromagnetic, gravity， CEMP and seismic data, the No.2 fault in Yitong graben was part of Xilamulun River fault extending eastwards in Jilin Province. The left-strike faulting of Jiamusi-Yitong graben causes the activities of Xilamulun River fault to form No.2 fault. As the differential subsidence of its hanging wall and footwall, the present configuration of No.2 fault evolves. As an important synsedimentary fault in Yitong graben, No.2 fault controls the hanging wall and footwall deposition and petroleum accumulation. No.2 fault and hanging wall formed a steep fractured slope-break belt, which controls sedimentary distribution of the hanging wall. Incising to basement, No.2 fault connects petroleum source rock of both Shuangyang and Sheling Formation. The formerly opening of No.2 fault is favorable for petroleum migration, and later sealed when the basin reversed. The No.2 fault plays an important role in the process of petroleum accumulation at Liangjia structural area.

Key words: Tancheng-Lujiang fault zone, Xilamulun River fault zone, Yitong graben, No.2 fault