Danshensu is one of the water soluble salvianolic acids which is extracted from Salvia. In this article, the interaction between Danshensu and bovine serum albumin (BSA） in aqueous solution was investigated by ultraviolet spectra and synchronous fluorescence spectra. Ultraviolet spectra showed that Danshensu could interact with BSA to form a stable complex. Fluorescence spectra showed that,with the increased concentration of Danshensu, fluorescence intensity (Δλ=15 nm) increased significantly and the maximum emission wavelength was stable at 285 nm,it is right for calculation the binding parameters of Danshensu-BSA. As Δλ=60 nm, the emission spectrum of Danshensu-BSA system showed a blue shift but the fluorescence intensity increased unobviously.The binding parameters of Danshensu-BSA were calculated based on the data of synchronous fluorescence spectra for the first time. The binding constants at 298, 308 and 318 K were 1.43×106, 1.25×106,5.00×105 L/mol, respectively. The thermodynamic parameters (ΔH=-10.28 kJ/mol, ΔS>0） implied that electrostatic force should be the predominant intermolecular force stabilizing the Danshensu-BSA complex．