The Ordovician fault- karst reservoirs in Tahe oilfield is an important object of oil and gas exploration and development in Tarim Basin.The paper analyzes the strike- slip faults in the western area of Block 10, Yuqi and the area of Yuqi 8 well in Tahe oilfield from the 3D seismic data. On this basis, a new understanding of the formation, evolution and genesis mechanism of the strike- slip fault system in Tahe oilfield is obtained. The results show that: ① In addition to the typical “X” type symmetric conjugate strike- slip fault system developed in the area of Block 10 and the Tuoputai in the south of the Tahe oilfield, the asymmetric conjugate strike- slip fault system has been discovered in the Yuqi area in north of Tahe oilfield for the first time. According to this, the south and north strike- slip fault systems in Tahe oilfield are divided. However, there are obvious differences in the formation time, maximum principal stress direction and dynamic source of the two fault systems. ② The formation and evolution of the two strike- slip fault systems can be divided into three stages: the two groups of symmetrical “X” conjugate strike- slip fault systems of NNE and NNW formed in the south of the middle Caledonian (Stage I), which were mainly affected by the subduction of the West Kunlun Ocean, and the maximum principal compressive stress direction was N3°E; Late caledonian to early hercynian produced mainly by the south tianshan ocean subduction subduction of the extrusion from N to S form of maximum principal compressive stress direction for N23 ° north nearly NE was given priority to, a small amount of SN to non symmetric conjugate strike- slip fracture system and late hercynian inherited but principal stress direction remains the same; The indosinian and Yanshanian strike- slip fault systems were mainly affected by the closure of the Southern Tethyan Ocean, resulting in the continuous activities of the two strike- slip fault systems, and the maximum principal compressive stress direction was N37°E. ③ The properties and activities of two groups of the “X” type symmetric conjugate strike- slip faults in different periods in west F1 (NNE) and F2 (NNW) in the western area of the Block 10 were analyzed semi- quantitatively by using the theory and method of generalized shear activity criterion. In the middle Stage of Caledonian (Stage I), F1(NNE) and F2 (NNW) groups were formed initially by coulomb fracture (activity coefficient fa=1. 0) under shear action. During the late Caledonian to Hercetic period, F2 (NNW) fault produced compression- torsion activity (activity coefficient fa=1. 1), which resulted in overall inactivity of F1 (NNE) fault (activity coefficient fa=0). During the Indosinian- Yanshanian period, the F1 (NNE) fault was tension- torsion active (activity coefficient fa=2. 1), resulting in the overall inactivity of F2 (NNW) fault (activity coefficient fa=0. 6). Therefore, the distribution, formation and evolution of the strike- slip fault system as well as the activity intensity in different periods are clarified in this paper, which can lay a better foundation for the exploration and development of the fault- solution reservoir in the Tahe oilfield.