Abstract: The effects of specific factors (including equipment, emulsifier, additives and asphalt content) on the stability of emulsified asphalt for cement and asphalt (CA) mortar were studied. Results showed that the emulsifying equipment, the amount of emulsifier, the type and amount of additives and asphalt content had great influences on the stability of emulsion, the optimum preparation conditions of emulsified asphalt were using SD-2 emulsifier with a dosage of 3.5%, an association thickening agent T of 0.4 %, a cellulose sodium (CMC) of 0.06 %, an asphalt mass fraction of 60% and applying colloid mill. The qualities of emulsified asphalt obtained under such conditions and CA mortar prepared by said emulsion could well meet the requirements of relative specifications issued by Ministry of Railways.