With 8%emulsifier,difenoconazole 10%EW was made up under different shearng speed and time and the distribution of particle size was measured with a laser particle size measurement.The results showed that the optimum speed and time were 3000r/min and 3min.Keeping the shearing speed and time unchangeable,the impact of the amount of emulsifier on the distribution of particle size was tested.The result showed that when the emulsifier was increased,the particle concentrated much more.And 8% emulsifier can give a better particle size distribution.