Abstract: Mechanism of the interaction between 3 flavonoids, i.e., luteolin, apigenin and puerarin, with bovine serum albumin (BSA) under different temperatures (292 K and 311 K) was studied by UV-VIS spectrophotometry and fluorospectrometry. It was found that the formation of the complexes led to quenching of fluorescence of BSA, which was proved to be a process of static quenching by the fitting equations of Stern-Volmer and double logarithm equation. The binding constants, number of binding sites, types of binding force and binding distances were found by applying the equation of site-binding model, thermodynamic equations, and Frster theory of transfer of non-radiation energy.