In order to satisfy the exploitation of unconventional energy shale gas in China, a set of oil-based drilling fluid system suitable for drilling in shale layer was developed independently. Comparison of Halliburton INNOVERT system of oil based drilling fluid, domestic oil-based drilling fluid has better thermal stability in a certain temperature range.According to the laboratory study and the field application of Weiyuan-Changning block, the domestic oil base drilling fluid CQ-WOM has the better ability to inhibit the shale hydration and dispersion;The sealing performance of the filter is excellent, and the filter loss of high temperature and high pressure is less than 3.5mL (test temperature 120℃), which can reduce the damage to the reservoir;This system has a good emulsion stability, ES value is greater than 1000V; The resistance to debris contamination ability is strong; Maintenance and treatment processing is simple and workable.