The hydroxyl in polysaccharide and flavones that extracted from Artemisia argyi can absorb onto the surface of silver nanoparticles and prevent aggregation from nanoparticles. The stable nano-silver solution was got. The preparation of Nano-silver Artemisia Argyi by Artemisia Argyi extract in alkaline and acidic environment was investigated, and the antibacterial property of fabric finished by the nano-silver Artemisia Argyi was analyzed. The experimental results show that the silver nanoparticles prepared in alkaline environment has small size with the minimum 12nm and uniform dispersion. The fabric finished by Nano-silver Artemisia Argyi exhibited strong antibacterial activity against E.coli and S.aureus, the sterilized rate was over 99.9%. The fabric has excellent antibacterial washability too.