Abstract: The wool fibers were carved and corroded to get rough surface by using ult raviolet radiation. So the antibacterial wool fibers were prepared by graf ting the nanometer silicon dioxide silver-loaded antibacterial agent . Thephysical , antibacterial and washable properties were characterized by using SEM , IR , etc. The surface layer of 200nm thickness was const ructed , and the nanometer antibacterial agent s are connected with the wool fibers by thechemical bonds. And the nanometer antibacterial agent is not simply attached to the surface by physical adsorption.The antibacterial efficiency of Escherichia col i and S taphy lococcus aureus is up to more than 96 % without washing ,and it is more than 90 % af ter repeated washing (at least 20 times) .