Experiments described in this paper show that carbon isotope composition of gaseous hydrocarbon from artificial maturation is similar to those from natural maturation.The same as that of natural gas

carbon isotope composition of pyrolyzed hydrocarbon can be used to indicate the type and maturity of organic matter in source rocks.Based on the re-sults of the experiments of thermal simulation of 8 source rock samples

the relationship between the yield of gaseous hydrocarbon

their carbon isotopic composition and the type

the maturity of organic matter in source rock is established

and then δ

13

C-value of both the pyrolyzed gaseous hydrocarbon in source rock and natural gas samples are used to study the natural gas and source rocks in Tarim and South Songliao Basins respectively.