Well Guiliudi-1 is a shale gas geological survey well in Luorong town block, Yufeng district, Liuzhou City, Guangxi province. The designed well depth is 2350m, and complex formations such as water sensitive strata are encountered during drilling. In order to improve the ability of solid-free drilling fluid to maintain the stability of hole walls in deep hole drilling in complex formation of shale gas geological survey， drilling fluid treatment agents such as the film-forming agent A and the plugging agent GFD-1 were added to the solid-free flushing fluid of PVA1788 system. Test and field application showed that the film-forming agent A had the function of reducing water loss without affecting the lubrication performance of the flushing fluid， or any obvious effect on the viscosity. The PVA1788 film-forming system solid-free drilling fluid has low filtration loss， good fracture sealing effect， reduces formation hydration expansion， and improves sloughing inhibition and prevention ability with film-forming； meeting the needs of maintaining the stability of the hole wall and safe drilling in the deep hole and complex formation. This paper has reference value for the popularization and application of solid-free drilling fluid in similar complex formations.