The interactions of Salvianolic acid A (SAA) and Salvianolic acid B (SAB) with insulin were studied by using fluorescence spectroscopy, UV-vis spectroscopy and ATR-FTIR spectroscopy in simulating physiological condition (pH 7.40). The fluorescence quenching of insulin by SAA and SAB were static quenching process. The results of synchronous fluorescence and three-dimensional fluorescence spectra suggested no obvious conformation changes of insulin after SAA or SAB binding. But ATR-FTIR spectra showed that SAA and SAB could change the secondary structures of insulin, of which β-turns decreased and random coil increased accompanied with α-helices and β-sheets no clear change. The glucose might influenced the the bioactivity of insulin in the SAA-insulin and SAB-insulin systems by changing the binding constants of SAA (or SAB) with insulin and exacerbating the changes of insulin conformation and relative contents of α-helices.