Abstract: In order to further enhance the exploration effect of unconventional oil and gas resources in Yanchi Block of Ordos Basin, the technical difficulties of drilling of horizontal wells in deep shale gas reservoir were analyzed. On this basis, the "two-stage polycrystalline diamond compact (PDC) bit and single bended screwdrill" technique was used to improve the sidetracking efficiency, the “multi-size bridge plug + fiber cement” technique was optimized to enhance the plugging effect and lower the cost, the high-performance nano-plugging water-base drilling fluid system was developed to realize safe drilling of horizontal sections in shale gas reservoir, and a customized PDC bit was designed, combined with PowerDrive Orbit for the application in horizontal section drilling. With all above efforts, the key drilling technology for the deep shale gas reservoir was formed. The technology was tested in Well Zhongping 1 in Yanchi Block, and a good field application effect was achieved for it improved the sidetracking efficiency and significantly reduced downhole failures. The test result show that the key technology can solve the technical difficulties in the dilling of horizontal wells in deep shale gas reservoirs in Yanchi Block, and it plays an important role in enhancing the exploration effect of unconventional oil and gas resources there.