Micro-emulsion has been used in EOR as oilfield agent for decades，but not in drilling fluid. Wellbore instability and high friction have been encountered frequently during the drilling process in horizontal and directional sections. Common agents used in drilling fluid cannot meet the demands of plugging and lubrication at the same time. A nonionic microemulsion WR-Ⅰwas developed based on compound surfactants of Span-80 and Tween-80 aided with co-surfactant of nbutanol.The effect of the nonionic micro-emulsion WR-Ⅰon the performance of drilling fluid was investigated，focusing on its plugging and lubricating properties. The results show that the nonionic micro-emulsion WR-Ⅰhas good performance including super-low interfacial tention of 0.005 mN/m and median size of 75 nm. It has little influence on the rheology of the drilling fluid and can lead to a small reduction in filtration loss. It can stabilize the wellbore of the shale section by quick adsorption and effective plugging with a blocking ratio of 95%. It has good lubricating property with an extreme pressure lubrication coefficient of 0.051 and a sticking coefficient of 0.138，which can effectively decrease the friction between drilling tools and wellbore as well as drilling cuttings.