The interaction of phlorizin with human serum albumin（HSA） was studied by fluorescence spectrometry,UV-visible absorption spectrometry and synchronous fluorescence spectrometry.The results showed that phlorizin could induce an endogenous fluorescence quenching of HSA under a mechanism of static quenching.The binding constants were determined to be 3.163 5×105（293 K）,1.774 8×105（303 K） and 1.193 5×105（313 K） L?mol-1,respectively.The binding site（n） was about 1.The thermodynamic parameters suggested that the interaction forces between phlorizin and HSA were mainly hydrogen and vander waals force.The binding distance was estimated to be 3.97 nm according to F-rster nonradiation energy transfer mechanism.The results of synchronous fluorescence spectra of phlorizin-HSA system showed that phlorizin mainly interacted with tryptophan in HSA,leading to a local change in protein conformation.In addition,the addition of the common ions could affect the binding constant of phlorizin-HSA complex.