Abstract: Based on the data of outcrops, cores and imaging logs, structural fractures and diagenetic fractures develop in the tight sandstone reservoirs of Chang?7 member of Yanchang formation in Ningxian-Heshui area in Ordos basin, of which the high?angle shear fractures are dominant, with four sets of orientations like EW, SN, NW-SE and NE-SW, dominated by NE-SW and EW fractures. The big variation of fractures is affected by the lithology, bedding thickness, sedimentary micro?facies and rock heterogeneity, among which the rock heteroge?neity is the main factor affecting such a reservoir’s fracture development degree. Also, the development of natural fractures of Chang?7 member is subjected to the effect of current stress field. The preferential open NE-SW fracture system will be the main seepage channels.The high rock brittleness index is favorable for volumetric fracturing, forming complex fracture network system in it