Abstract: The low?cost strategy is the core of development of tight oil. The experience from successfully developing tight oil in USA shows that the combination of suitable engineering technique and factory operation mode is the effective ways to reduce the cost. In order to further reduce the development cost, Changji oilfield tight oil test area in Xinjiang has employed the large cluster platform horizontal wells to meet the need of the factory operation mode. According to the geologic characteristics of tight oil of Permian in Changji oilfield, this paper introduces the key technologies such as optimizing the structure of the hole, PDC bit type selection, selection of horizontal well azimuth, optimal design and fine control of 3D trajectory, anti?collision of cluster horizontal wells and optimization of drilling fluid systems. The well structures turn four into three by field experiment. Compared with the previous, the average rate of penetration is increased by 2.43 times, drilling duration is reduced by 82.75 d. The conventional deflecting tools meet the demands of well trajectory control of 1 300~1 800 m horizontal section, and the drilling costs are greatly cut. All of these create favorable conditions for effective development of Changji oilfield tight oil