Abstract: Bentonite loading nanosilver（ Nano-Ag/BT） antibacterial agent was prepared using silver nitrate solution and acid treated bentonite under UV light irradiation by photochemistry reduction method with bentonite as template and sodium dodecylbenzene sulfonate as dispersant and stabilizer. The structure and properties of Nano-Ag/BT were characterized by Scanning Electron Microscope,High Resolution Transmission Electron Microscope and Energy Dispersion Spectrometer. The results show that the spherical nanosilver was interposed into the interlayers of bentonite with the sizes in 3-20 nm and most of the nanosilver sizes less than 8 nm. The nanosilver content of the Nano-Ag/BT was 2.04 wt%. The NanoAg/BT had good antibacterial properties against E. coli（ ATCC8099） and S. aureus（ ATCC6538）. The Minimal Inhibitory Concentration（ MIC） for Nano-Ag/BT are 25μg/m L against E. coli and 50μg/m L against S.aureus. It can inhibit the growth of bacteria quickly.