The interaction between pentachlorophenol and bovine serum albumin (BSA) were studied using fluorescence spectra and ultraviolet-visible light absorption spectra. The results show that the fluorescence of BSA was quenched regularly by the pentachlorophenol, the mechanism of the fluorescence quench was investigated. The binding constants and thermodynamic parameters of pentachlorophenol with BSA were obtained at different temperatures. The hydrophobic interaction force and electrostatic force played a main role in the binding of pentachlorophenol with BSA. The distances of binding site between pentachlorophenol and BSA were also obtained according to the theory of Forster's non-radiative energy transfer.