Abstract: Three kinds of chemical modified silica gel, Si-O-C_(10)H_(21)-n(Ⅰ), (Ⅱ) and Si-O-SiMe_3 (Ⅲ), were prepared. Fluorescence and lifetime of pyrene on these silica, gel were investigated. Exeimer emission of pyrene was formed from two pathways, excited groud state aggregate and excited monomer with groud state monomer. Groud state aggregate on silica gel Ⅲ was more than on silica gel Ⅰ in same concentration. Pyrene was dispersed as monomer in wide range coneentration when chemical modified silica gel adsorbed 1-decanol and excimer formation was controlled predominantly by dynamic process. Activated energy of excimer formation is 7 kcal.mole~(-1). Effect of temperature on fluorescence and lifetime of pyrene was studied. Effect of topochemical environment on fluorescence vibrational structure of pyrene was discussed.