Temperature-programmed simulation experiments of saturated hydrocarbons with calcium sulfate and element sulfur were compared in this study. Based on the variation analysis of the yields and evolvement features of gaseous hydrocarbon (C1-C5) and inorganic gaseous CO2, H2 and H2S, the reaction mechanisms were analyzed and discussed. In the calcium sulfate-saturated hydrocarbon system, H2S was produced by a small quantity, which indicates this reaction belongs to the low-degreed thermal sulfate reduction (TSR) and is featured of self-pyrolysis. In the sulfur-saturated hydrocarbon system, the heated sulfur becomes sulfur radical, which has strong catalysis capability and can fasten the cracking of C―H bond in the alkyl group in the saturated hydrocarbons. As a result, the cracking of C―H bond leads to the yields enhancement of CO2 and H2, and at the same time, H2S was produced since the cracked hydrogen can be instantly combined with sulfur radical. Therefore, this reaction in the sulfur-hydrocarbon system belongs to the catalysis of sulfur radical. Furthermore, the promoted pyrolysis effects of C6+ hydrocarbons by sulfur radical in the low-temperature stage in the sul- fur-hydrocarbon system, together with the consumption effects of gaseous hydrocarbon in the high-temperature stage in the calcium-hydrocarbon system, result in the crossed phenomenon of the gaseous hydrocarbon yields curves. Temperature-programmed simulation experiments of saturated hydrocarbons with calcium sulfate and element sulfur were compared in this study. Based on the variation analysis of the yield and evolvement features of gaseous hydrocarbon (C1-C5) and inorganic gaseous CO2, H2 and H2S, the reaction Mechanisms were analyzed and discussed. In the calcium sulfate-saturated hydrocarbon system, H2S was produced by a small quantity, which indicates this reaction belongs to the low-degreed thermal sulfate reduction (TSR) and is featured in self-pyrolysis. In the sulfur -saturated hydrocarbon system, the heated sulfur becomes sulfur radical, which has strong catalysis capability and can fasten the cracking of C-H bond in the alkyl group in the saturated hydrocarbons. As a result, the cracking of C-H bond leads to the render enhancement of CO2 and H2, and at the same time, H2S was produced since the cracked hydrogen can be instantly combined with sulfur radical. Therefore, this reaction in the sul Fur-hydrocarbon system belongs to the catalysis of sulfur radical. The promoted pyrolysis effects of C6 + hydrocarbons by sulfur radical in the low-temperature stage in the sul-fur-hydrocarbon system, together with the consumption effects of gaseous hydrocarbon in the high -temperature stage in the calcium-hydrocarbon system, result in the crossed phenomenon of the gaseous hydrocarbon yield curves.