Silica nano-particles have been prepared by using E. colon bacillus (E. coli) as template. The particles accumulated on the inner wall of E. coli's cells. Their formation is related to the kinds of silicates. Sodium silicate can neither promote the breeding of E. coli nor provide the opportunity of silica formation. In contrast, tetraethylorthosilicate (TEOS) can easily be converted to silica. 100mg/L of aqueous TEOS appear to be an optimum concentration for the growth of E.coli.and silica formation.