Abstract: In order to further reduce costs and increase efficiency, the tests on secondary casing program of horizontal wells and the optimization of casing cementing and completion were carried out in Dongsheng gas field. Based on the construction difficulties, combined with the theoretical analysis of mechanics, and the key technologies such as physical-chemical compound leakproof and collapse prevention, PDC bit with high efficiency selection techniques, and long open hole cementing techniques were optimized formed by laboratory experiment and mechanics analysis. The field application shows that the construction of six wells is smooth and no complex situation occurs. Compared with the three-stage casing program of horizontal wells in the same period, the drilling cycle is shortened by 34.98 d, the mechanical drilling rate is increased by 1.78 m/h, and the cost of drilling and completion of a single well is saved by more than 357,000 yuan.