Abstract: A total of 31 horizontal wells have been drilled on Hua H100 platform in Qingcheng Oilfield in Ordos Basin. For the first time, the cross-layer fracturing is tested in four horizontal wells on this platform with low drilling rate of reservoir. Meanwhile, by applying tracer monitoring technology, the engineering feasibility of penetrating mudstone and communicating the adjacent sandstone reservoirs and the effectiveness of flow pathway after fracturing are analyzed, and the production contribution of the cross-layer fracturing stage is evaluated. The pilot test results show that when the distance between the horizontal well trajectory in the non-reservoir interval and the sandstone reservoir is less than 3 m and the clay content is lower than 40%, the cross-layer fracturing engineering is feasible. A total of 14 stages have been tested and good results have been achieved in 12 stages, with a success rate of 85.7%, confirming the feasibility of cross-layer fracturing operation. The tracer detection and interpretation results show that continuous water flowback has been monitored in cross-layer fracturing stages, which indicate that an effective flow pathway has been formed after soaking the well. The varying amounts of oil production in various cross-layer fracturing stages also demonstrate that the sandstone reservoirs have been communicated by cross-layer fractures, with a definite production contribution. Compared with another four offset wells with drilling rate of higher than 80% on the same platform, the cumulative oil production of cross-layer fracturing wells is above the average level. The successful pilot test of Hua H100 platform proves that the cross-layer fracturing is an effective engineering means to increase single well production of horizontal wells with low drilling rate of reservoir.