The formation mechanism of the Cenozoic structure in the Biyang Depression is discussed according to the latest structural theories and research methods. The Biyang Depression superimposes the Qinling orogenic belt, and its stratigraphic sequence suggests that its extension process can be divided into six extensional episodes. Before the 2nd member of the Hetaoyuan Formation (Eh 2, middle Oligocene), the structural deformation was influenced by a NE-SW extensional stress and controlled by the Tanghe-Liyuan Fault, which was a normal fault with a left lateral slip component. From the H 2 member to the end of the Liaozhuang Formation (El, upper Oligocene), the structural deformation was influenced by a NW-SE extensional stress and controlled by the Biyang-Liyuan Fault, which was a normal fault with a right lateral slip component. During this period, the earlier structural styles were reformed in the deformation of the hanging wall of the Biyang-Liyuan Fault. At the end of El, influenced by a NW-SE extensional process, a regional uplift and fault block tilting led to the erosion of the strata. Since period Eh 2, particularly from the end of El, as the result of the heterogeneity of the NW-SE extension, a NW strike-slip fault became active, and influenced the structural activity of the cover.