The microphase adsorption-spectral correction (MPASC) technique was described and applied to the study of the interactions of sodium octanesulfonate (SOS) with human serum albumin (HSA). The aggregation SOS obeys the Langmuir monolayer adsorption. The results show the adsorption ratio of sodium octanesulfonate to HSA is SOS:HSA=18:1.The adsorption constant is K(SOS-HSA)=4.03 × 10(2). The detection limit is 0.036μmol/L. FT-IR spectra proved the binding changed the conformation of HSA.