Phenolic compounds from natural plants have good antibacterial effect on drug-resistant bacteria. Syringic acid (SGA) is a typical representative of natural phenolic acids. In this paper, waterborne polyurethane films (SWPU) were prepared by quaternization reaction of isophorone diisocyanate (IPDI), polytetrahydrofuran glycol (PTMG) and 1mai 4-butanediol (BDO) with chain extender 3-dimethylamino-1-mino-2-propanediol (DMAD) and SGA. SWPU films were characterized by FTIR and 1H-NMR. The nano-size, DSC, mechanical properties, water contact angle and antibacterial properties of SWPU films were analyzed. The results showed that the glass transition temperature of SWPU-3 film prepared at n (DMAD): n (BDO) = 5:1 was -29.02 ℃, the water contact angle was 79.1 °, the tensile strength was 35.6MPa, the elongation at break was 987.7%, and showed more than 99.1% antibacterial activity against Escherichia coli and Staphylococcus aureus. The antibacterial zone experiments show that the antibacterial mechanism of the film is based on contact killing rather than the release of antibacterial components, and the sample film has environment-friendly characteristics.