[Objective] The properties of butachlor microemulsion were studied for developing a new formulation of new pesticides.[Method]AT method was used to determine the pseudo-ternary phase diagram to confirm the formulation of butachlor microemulsion.Through the measurement of electrical conductivity,the W/O and O/W types in microemulsion region of butachlor/emulsifier/water system were confirmed and the change of phase behavior during preparation process was discussed.[Result]The dilution stability,low temperature stability,heat stability,ageing stability,density and viscosity etc.of butachlor microemulsion met the requirement of the experiments,which demonstrated the qualified quality of butachlor.The density decreased linearly with the increase of temperature and the change of viscosity with temperature conformed to Andrade equation.[Conclusion]The research was helpful to the application of butachlor microemulsion in pesticide formulation.