Abstract: In the study of hydrocarbon-generation dynamics, it is needed to make quantitative analysis, qualitative anakysis and simple-hydrocarbon carbon-isotopic analysis on minor or trace hydrocarbon gases generated from thermal simulation.The gases in gold tubes were collected and quantified by a Toepler mercury pump, and then were sent into a gas chromatogaph to make compositional analysis.The residual gases were collected and transferred so as to make carbon isotopic analysis.In this paper, the detailed structure and operating mechanism of the system were introduced, and several factors affecting analysis precision were discussed.