Since the development of Gulong shale oil in the northern Songliao Basin， due to the geological characteristics of the formation and the limitation of drilling technology，the horizontal wells in the test area all adopted three-layer casing well structure， and the 2000~2500m horizontal section of long horizontal wells have a 100% “one-trip drilling” ratio in ?311.2mm boreholes. The “one-trip drilling” technology of the ?215.9mm boreholes has gradually transited from the initial “one-trip drilling” of the inclined section and the horizontal section respectively to that of the inclined section+horizontal section. With the improvement of drilling technology of shale oil wells’ ?215.9mm boreholes， in order to further shorten drilling and completion period and reduce drilling investment， the application and practice of three-spudding to two-spudding and “one-trip drilling” of ?215.9mm hole was optimized in Well GY15-Q8-H1. In this paper， the optimization design process， technical difficulties， risks and practical understanding of countermeasures of Well GY15-Q8-H1 well are described in detail， which provides a reference for the improvement of shale oil three-spudding to two-spudding drilling technology and the reduction of drilling construction complexity.