In this study, silver nanoparticles were synthesized by chemical method (chemical reduction method) using AgNO3 and BH4as starting materials in the presente of Sodium dodecyl sulfate (SDS) as a stabilizer. The obtained Ag nanoparticles were characterized by UV/Vis absorption at about 400 nm. Ddifferent concentrations of silver nitrate (0.1 mM, 0 and 2 mM, 0.5 mM, 1 mM) were used as initial concentration. The stability of AgNPs was measured by UV up to 3 months. The intensities of the Surface Plasmon Resonance(SPRs) progressively increase with temperature, and the position of SPRs was red-shifted to longer wavelength. In addition The absorption was increased with an increase in pH and gives the narrow peak at pH 7-8. Hence, the neutral condition is favored for controlling the particle size. The results showed that, the AgNPs have antibacterial activity against E. coli (Gram negative bacteria).