Abstract: It is a correct argument that Huayingshan fault zone is a fundamental fault.The zone can be horizontally divided into three distinct parts,i.e.central,southern and northern parts.The central part,known as Xishan-Huaying-shan part,is the main one,and the major fault of the Xishan structure penetrates through the cap rock and extends into the basement.In the belly of the west side of the Huayingshan fault zone,because of the extrusion of the fault zone,many hidden faults and structures have been formed,thus the accumulation condition of oil and gas has been improved.In the east side of the Huayingshan fault zone,the structure moderately folded has better conditions for the accumulation and preservation of oil and gas.Pore,cave and fracture are well developed due to the frequent movement of the Huayingshan fault zone,resulting in an improved accumulation condition of oil and gas.