Using isophorone diisocyanate (IPDI), polytetrahydrofuran ether glycol (PTMG), dimethylol butyric acid (DMBA), 1,4-butanediol (BDO) and self-made red anthraquinone dye (DYE-R) as monomers to synthesize polyurethane (PU), and 2-hydroxyethyl methacrylate (HEMA) as end-capping agent, double-bond terminated waterborne polyurethane was prepared, and then soap-free emulsion polymerization method was adopted. The results showed that with the increase of PA content, the particle size of the emulsion increased. When m(PU):m(PA) was 10:2, the particle size of the emulsion was 81 nm, which had good stability and certain alkali resistance. The emulsion has obvious coloring effect, the thermal mobility is 3.54%, and the color fastness to dry and wet rubbing is 4 ~ 5 grades. When the mass retention rate of the emulsion film is 50%, the corresponding temperature is 396.1℃, and m(PU):m(PA) is 10:2, the comprehensive performance is the best.