As the important parameters of controlling the quality of emulsified asphalt, the particle size and distribution of emulsified asphalt have the important effect on the storage stability and using performance of emulsified asphalt. The particle size variation characteristics of emulsified asphalt in the storage process are studied through the stratified particle size test. It is found that the average annual particle size of emulsified particle size increases with the time increment and with the depth increment, and decrease with the increment of emulgator content. The study result provides the theoretical reference for the production, storage and construction of emulsified asphalt.