Abstract: The interaction between propyl gallate( PG) and BSA was studied by the spectroscopy method in vitro.The quenching mechanism was a static quenching procedure,and the binding constants KAbetween PG and BSA was obtained to be 1.03 × 105L·mol- 1while the binding distance was calculated as 2.2 nm at 299 K. The thermodynamic calculations suggested the van der Waals interactions and the hydrogen bonds play a major part in the interaction between BSA and PG.The further study of binding site showed there was one PG- binding site in the subdomain IIA of BSA. CD spectroscopic further showed that drug complexation altered protein conformation by a major reduction of α- helix inducing a partial protein destabilization. In addition,the result of autodocking for PG and BSA was simulated,and the parameters of the binding were accorded with the results of the calculation.