Silver/waterborne polyurethane-acrylate (Ag/WPUA) coating was firstly synthesized by a novel and facile method of combining in-situ reduction and polymerization reactions. Cotton fabrics were pre-treated to introduce SH groups by the reaction between the OC2H5 groups of 3-mercaptopropyltriethoxysilane and OH groups of cotton fabrics. Then antibacterial finishing of cotton fabric was obtained with Ag/WPUA coating under ultraviolet (UV) radiation where click reaction was taken place between SH groups and CC bonds. Ag/WPUA coating was characterized by transmission electron microscopy (TEM), Fourier transforms infrared spectra (FTIR) and X-ray diffraction (XRD). The chemical bonding, antibacterial property, thermal stability and mechanical property of antibacterial cotton were investigated. The results of antibacterial test elucidate that the bacterial reduction was 99.99% for E. coli and S.aureus, revealing that the finishing on cotton fabrics has excellent antibacterial activity. Furthermore, the antibacterial cotton fabrics still maintains good mechanical properties like breaking strength and thermal stability.