Abstract: The nano-silver antibacterial material has been widely used in various fields, and has certain biological safety. The process about the antibacterial mechanism of silver nanoparticles is more complex,which main includes oxygen consumption of the living environment of bacteria, destruction of cell wall and cell membrane, inhibit the replication of DNA molecule and activity of enzyme. The preparation method of nano-silver has physical, chemical, biological and other methods, in which the biological reduction method is a new preparation technique, in line with the concept of green environmental protection, and is a hot spot in the future research. The antibacterial property of nano silver is influenced by many factors, including silver particle size, morphology, strain, protective agent and so on.