A series of UV-cured cationic waterborne polyurethanes(UWPU) were prepared by biological resource castor oil. In order to further improve its antibacterial properties，the antibacterial UV-curable castor oil-based waterborne polyurethane（GWPU）was successfully prepared by introducing guanidine group in the reverse process of polyurethane prepolymer emulsification. The performance of the films were evaluated by a series of measurements，including water resistance test, inhibition zone test and antibacterial property test. The results showed that the water absorption rate of GWPU film relative to UWPU increased, but they remain below 10%; GWPU films were a contact antibacterial material, without antibacterial substance leaching; the antibacterial rate of GWPU films against S.aureus and E.coli was up to 99.9% when adding 1.2% aminoguanidine, and after antibacterial durability test can still maintain 99.9% antibacterial performance.