Abstract: In view of the problems of high cost, long drilling cycle, slow ROP, unstable borehole wall, high friction and torque, and difficult casing running in tight oil reservoirs of Jilin Oilfield, this paper studies the optimized drilling and completion technology for for horizontal wells with two-section casing program and long horizontal section. In order to reduce the cost and shorten the drilling cycle from the engineering design, the three-section casing program used in the early stage was simplified to a two-section one with shallow surface casing, and one section completion time was saved. At the same time, the technical measures such as optimal design of borehole trajectory, low-filtration strength suppression polymer drilling fluid system, near-bit geological guiding tool, customizing the PDC bit design, floating casing and cementing and so on were formed.The technical measures were applied in 180 horizontal wells in tight oil reservoirs of Jilin Oilfield, with an average well depth of 3449 m, an average horizontal length of 1189 m, a casing safety entry rate of 100%, a cementing qualified rate of 100%, increasing in reservoir drilling rate by 20.2 percentage point, shortening drilling cycle by 44.2% and reducing investment costs by 40.7%. The research results achieve the goal of low cost and high efficiency development of tight oil reservoirs in Jilin Oilfield, and can provide a reference for the development of unconventional reservoirs such as tight gas and shale oil.