Abstract: Added Internal standard sample to the saturated hydrocarbon fractions which are obtained through silicon-alumina column chromatography in crude oil or extraction asphalt "A",then carried out the GC-MS quantitative analysis of biomarkers.The results indicate that quantitative analysis errors of the steranes and hopanes are less than 10%.This method is applied to the GC-MS quantitative analysis of biomarkers for expulsive oils during thermal simulation of rocks.The results show that the contents of biomarkers gradually decrease with the rising of simulation temperature,but the situation is basically stable after 350℃.The ratio of Ts/(Ts+Tm) increases with the rising of simulation temperature.