This paper presents the study of SEES of pyridine on silver island film prepared by chemical deposition on island photoresist. We observed the influence of the separation of silver island on enhancement, and analysed the SEES spectra obtained at different times of laser illumination, including the changes of relative intensity and Eaman shifts. The results show that the island structure of silver film is in favor of enhancement, and that the adsorbed form of pyridine on silver film is transformed during the first twenty minutes laser illumination.