Removing oil-based mud adhered to borehole and casing walls efficiently is crucial to develop an excellent cement bond of the interface and cementing quality. When the surfactant and salty solution contacts with the oil，the surfactant can form interfacial film and wraps the oil，resulting in that the microemulsion is formed in situ. According to that，the microemulsions were prepared with sodium 2-ethylhexyl sulfosuccinate（AOT）and iso-tridecanol polyoxyethylene ether（AE05-13）as surfactants，diesel or white oil as oil phase. Solubilization parameter and interface tension of the microemulsions were investigated and a formula of microemulsion flushing fluid was prepared: KCl salty water + 4%AOT+ 3%AEO5-13 + 6% n-butanol. The wettability alteration ability，flushing efficiency and the compatibility of microemulsion flushing fluid was evaluated. The experiment results showed that the microemulsion phase varied from Winsor I to Winsor III and then to Winsor II with the increase of salt mass concentrations. The Winsor III microemulsion possessed the optimum solubilization parameter and interfacial activity，and the optimal salinity of Winsor III dieesel microemulsion and white oil microemulsion was 7% and 10%，respectively. The density and rheological property of microemulsion flushing fluid could be adjusted and its flushing ability was good. Performances evaluation showed that the wettability alteration ability of the flushing fluid was excellent，and the flushing efficiency for oil-based drilling fluid was higher than 95% in 7 min. The compatibility of microemulsion flushing fluid with oil-based drilling fluid and cementing slurry was excellent.