A gas chromatography-mass spectrometric(GC-MS) method was established for the determination of four main kinds of phytosterols(e.g.brassicasterol,campesterol,stigmasterol and β sitosterol) in vegetable oils.The phytosterols were transformed to the corresponding TMS derivatives and subsequently analyzed by GC-MS.The mass spectrometric fragmentation rule and mass characteristic ions of the derivatives were also studied.The method is accurate,reliable and convenient，and the detection limit was 0.01 g/kg.It was applied in the qualitative and quantitative determination of phytosterols in vegetable oils with satisfactory results.