Abstract: Characteristic of the fluorescence spectrum and UV-absorption spectrum of the compound complex formed between BSA and active ingredient of hops (a traditional Chinese medicine) was studied.It was found that the formation of the compound complex led to quenching of fluorescence of BSA,which was proved to be a process of static quenching.The experimental data were treated by the fitting equations of Stern-Volmer and Line-weaver-Burk separately,and the mechanism of static quenching of the interaction between BSA and hops was certified.Equilibrium constants and thermodynamic parameters of the binding reaction were also given.