In order to improve the emulsifying agent compatibility with epoxy resin, a series of nonionic waterborne epoxy emulsifiers with A-B-A (A is epoxy chain segment, B is hydrophilic chain segment) structure were synthesized by two-step method using polyethylene glycol (PEG6000, PEG4000, PEG2000), methyl hexahydrophthalic anhydride (MHHPA) and epoxy resin (E44) as raw materials. The structure of the emulsifier was characterized by infrared spectrum analysis, and the optimal synthesis process was determined by infrared spectrum analysis and acid titration: esterification reaction was carried out with PEG and MHHPA in the molar ratio of 1∶2.1 under the temperature of 110 ℃ for 3 h; then E44 in the same number of moles of MHHPA was added in and the epoxy ring-opening reaction was carried out under the catalyst tetrabbutylammonium bromide (TBAB, 1% of the amount of epoxy resin) at 110 ℃ for 3 h. Waterborne epoxy emulsion was prepared by using the synthesized emulsifier on epoxy resin E44. Then it studied the effects of relative molecular mass of PEG, emulsifier content, emulsifying temperature and stirring speed on the stability of the emulsion. After comprehensive consideration of emulsion stability, particle size and distribution, the results show that the emulsifier synthesized by PEG6000 has better emulsifying effect, with HLB value of 16.5 and turbidity point of 90 ℃, which is superior to PEG4000 and PEG2000. When the emulsion solid content is about 45%, the emulsifier content is 20%, emulsifying at 75 ℃ and stirring speed of 2 000 r/min, the water-based epoxy emulsion with small average particle size and narrow distribution can be obtained, and shows good emulsion stability.