Ellagic acid (EA) is a natural polyphenol with antioxidant， anti-cancer， anti-mutation， anti-inflammatory and other physiological activities. The interaction between ellagic acid and protein will directly affect its transport and metabolism in the human body. In this paper， a variety of spectroscopic methods and molecular docking simulation methods were used to study the reaction mechanism of the interaction between EA and bovine serum albumin (BSA). The results of UV spectroscopy and fluorescence spectroscopy showed that EA quenched the endogenous fluorescence of BSA in a static manner， EA and BSA combined to form a stable complex through BSA， resulting in the decrease of α-helix structure and the increase of β-sheet， β-turn and random coil structure in BSA. There may be hydrophobic interactions between them. Molecular docking simulation further verifies the results of the above spectral analysis， which shows that in addition to the van der Waals force and hydrogen bond， the dominant force for the binding of EA and BSA also has a certain hydrophobic force. The optimal binding site of EA on BSA is located in the hydrophobic cavity between subdomain IIA and subdomain IIIA， which is closer to site I. There are hydrophobic interactions between EA and residues such as His145， Pro110， and Arg458， and there are hydrogen bonds between residues of EA and Arg144. This study clarified the molecular mechanism of the interaction between EA and BSA， and provided useful information for the study of EA transport and metabolism in vivo.