The Raman spectra of BSA in 5% aqueous solution extracted by nitrobenzene have been studied. The amide I band appears at 1 651 cm-1,amide Ⅲ band appears at 1 292 and 1242 cm-1. The characteristic Raman bands of the tyrosine residue are at 856、828 and 643 cm-1. The band of the s-s bond is at 522 cm-1. All the characteristic Raman bands of mis protein peptide prove that its structure consists of a- helical and random- coil. The tyrosine residue is "exposed" and the conformation of the carbon atoms in the disulfide bridge C-C-S-S-C-C is trans-gauche-gauche.