Doubly Modified Waterborne Polyurethane Curing Agent was successfully synthesized with Hexamethylene diisocyanate (HDI) and Trimethylolpropane (TMP) as the main materials, Polyethylene Glycol 400(PEG400) as the nonionic modifier and sodium hydroxyerthyl sulfonate as the ionic modifier. The properties of the curing agent and films such as gloss, hardness, solvent resistance, and water resistance were significantly affected by the amount of PEG400,sodium hydroxyerthyl sulfonate and the reaction temperature , reaction time and the ratio of dispersion to curing agent. The optimum performance was obtained with the content of PEG400 and sodium hydroxyerthyl sulfonate reaching 15.8% and 3.17%, and the reaction temperature and time were kept at 80 ℃and 3h, and the ratio of curing agent to dispersion was 1.4~1.6. Furthermore, the synthetic process of the curing agent and film properties were characterized by FTIR and SEM, etc.