To obtain a structural basis for the β-casein in Chinese human milk, structural transitions of the β-casein in response to variation of pH were investigated using Raman and circular dichroism (CD) spectroscopy. Both methods indicated that the secondary structures of β-casein in the solution were induced by the pH. Secondary structural analysis of β-casein by CD spectroscopy yielded 0.5%~2% α-helical, 16%~18% β-sheet, 30%~34% β-turn and 49%~51% random coil contents. Another result was that as pH increases, these structures change. Several distinct transitions were observed by circular dichroism in α-helix at pH 8 and pH 10. Raman spectrum also showed random coil as the major secondary structure in native β-casein, for the characteristic band of the β-casein amide I was at 1 662 cm-1. Calculations from I850/I830 suggested that the tyrosine residues of β-casein tended to “exposure”. CD and Raman spectra both showed that at neutral and alkaline pH the β-casein existed predominantly in random coil conformation, and the proportion of α-helix was higher at pH 8 than under other pH conditions. Over the range of pH studied, the sheet and turn areas remained relatively constant, and in the condition of pH 8, the content of α-helical was higher than in the other pH conditions.