Abstract: The epoxy was modified by polyethylene glycol (PEG) to synthesize self-emulsifying epoxy emulsion, which was characterized by FTIR to confirm its structure. The stability of the epoxy emulsion stemmed in different experimental circumstances was investigated to analyze the effects of the reactants, process and other factors on the final products, and to reveal the optimal process parameters. The thermal properties of the sizing agents were characterized by TG and DSC, the wetting property of the sizing agents were characterized through contact angle test, and the IFSS (interfacial shear strength) of a single fiber was characterized by a single fiber fragmentation test. The results show that the emulsion prepared by reaction of the epoxy and PEG-1000 at 80~120 ℃ has the best stability. The sizing agents has good thermal stability and wetting property. The fuzz amount of carbon fiber decreases and the IFSS (interfacial shear strength) increases by 33.48% after sizing with the epoxy emulsion.