A single-component anionic polyurethane emulsion has been prepared from polyepoxyglycol, tolylene diisocyanate, dimethoxypropionic acid and ethylene diamine via prepolymeration route. The effects of the molecular weight of polyether polyol, the ratio of isocyanate group to hydroxy group and the amount of dimethylolpropionic acid on the property of the PU film and its physical property have been investigated.