The interaction between silver nanoparticles and Methylene Blue(MB)is studied by UV-Vis spectroscopy and fluorescence spectrometry.The UN-Vis absorption of the silver nanoparticles dramatically with the addition of MB.However,no obvious changes of absorption spectra of MB are observed when silver colloids ate added into the MB solution.In the presence of surfactant SDS,the catalysis of the silver nanoparticles in the reducton of MB by sodium borohydride is exhibited by UV-Vis and fluorescence spectroscopy of MB displaying faster response compared with the absence of the silver nanoparticles.The results show that the activity of surfactant SDS modified silver nanoparticles is great and a strong physical adsorption to MB exists.