Shale gas resource potential is tremendous huge in China. In recent years, the requirements of the drilling process and technology are continue to increase along with the efforts of exploration and development of shale gas and unconventional energy sources. Shale gas formation lithology is mainly mudstone, sandstone, shale, carbonaceous slate and limestone. Because of poor formation cementation, broken and low wall strength, hole wall instability, collapse and sticking or burying accidents were liable to happen in drilling process, the flushing fluid system with strong inhibitory, good compatibility, low cost, green environmental protection drilling fluids is needed in the drilling engineering construction. Based on the research on the mechanism of shale borehole wall stability, a low solid phase flushing fluid system with double polyethylene anti-sloughing and film forming anti-sloughing is optimized, which is suitable for shale formation. The system is consisted of inhibitors, anti-sloughing agent, agents, fluid loss additives, lubricants, blocking agents and flow pattern regulators with good inhibition and cementation. Good construction effects have been achieved in a number of field applications.