The silver and the silica by the special structure of KH-550 were combined. The silver was distributed in silica surface during the formation of silica, and then through the reduction of formaldehyde, silica doped silver antibacterial particles would be got eventually. The formation mechanism of nano-silica doped silver antibacterial particles, combined with SEM、TEM and other means were applied for analysis and characterization. The results showed that the size of compound particle was about 350nm in diameter, and the silver doped on silica surface was about 10nm, and compound particles contained about 13% silver (mass).