Abstract: OBJECTIVE To explore the interaction between amfebutamone and human serum albumin(HAS). METHODS Fluorescence spectrum was used to measure the effects of amfebutamone on the fluorescence quenching spectra and synchronous fluorescence spectra of HAS. Stern-Volmer equation was used to determine the mechanism of fluorescence quenching of HAS. The binding constants were calculated according to Lineweaver-Burk equation and types of binding force were estimated by the calculation of thermodynamic parameters. RESULTS The fluorescence quenching spectra showed that amfebutamone had quenching effect on HAS. The quenching rate constants were 5.714 8×10³, 3.126 1×10³ L·mol^-1·s^-1 at 17 ℃ and 37 ℃. The enthalpy changes and entropy changs were both <0. The binding site number of amfebutamone and HSA was 1. Conclusion The fluorescence of HAS quenched by amfebutamone is static and the interaction force between them are mainly hydrogen bond and van der waals force.