The relationship between the type of catalyst and temperature and the reaction time and conversion rate in the synthesis of reactive waterborne epoxy nano emulsifier was studied by titration of epoxy value with hydrochloric acid-acetone method.It was found that when boron trifluoride ether was used as the catalyst,the addition amount was 0.2%,the reaction temperature was 90℃,and the reaction time was 4 hours.Using PEG-6000 as the raw material,the emulsifier prepared at a molar ratio of 1.0-1.2 to E-51 has the best effect.The structure was characterized by infrared and nuclear magnetic resonance.