The method for analysis and determination the cleavage of soybean sterol, in which the soybean sterol was degraded and the products androst-1,4-diene-,17-dione (ADD) and androst-4-ene-3,17-dion (AD) were developed by Liquid Chromatography-mass Spectrometry. The HPLC conditions adopted were: a Alltima ODS-2 column (250 mm×4.6 mm, 5 μm), a mobile phase consisted of menthanol - water (70:30), a flow rate of 1.0 mL/min, a room column temperature. and the detective wavelength was 244 nm.The ZMD Micromass electrospray ionization (ESI)-mass spectrometer was employed. In such conditions the corresponding HPLC chromatogram and MS spectrum were obtained. The method has a linear ranger of 0.01 mg/mL ~ 0.09 mg/mL, R2 =0.9999, the recoveries of ADD and AD were 102.6% and 105.90%, the RSD of ADD and AD were 3.02%, 3.5% and 3.08%, 3.24%. This method showed high sensitivity, accuracy and easy to perform. It is suitable to analysis the process cleavage of soybean sterol as well as quality control of product.