Abstract: Thermochemical sulfate reduction (TSR), which is a complex organic-inorganic interaction in reservoirs, can not only generate H2S-bearing gas but also reform reservoirs by its sour gas products. This paper firstly studied the influence of TSR on the occurrence of oil-cracking gas by gold-tube pyrolysis. It was revealed that the redox reaction can evidently decrease the thermal stability of oil and accelerate the generation of natural gas with H2S and high dryness. It was confirmed that contact ion pairs (CIP) should be the most feasible oxidant in initiation reaction of TSR collectively by in situ Raman technology and pyrolysis experiments. The potential factors, which can dominate TSR reaction, were thoroughly discussed. It was found that the salts type and concentration in addition to oil compositions, labile organosulfur compounds (LSC) content should be the critical factors for occurrence of TSR. On the other hand, TSR was demonstrated to play an important role in the reformation of carbonate reservoirs on the basis of detailed geological observations. The corrosion mechanism by sour fluid was also revealed with the assistance of corrosion model experiments. Moreover, there was a secondary porosity zone formed by TSR in deep carbonate reservoirs. It is suggested that, the redox reaction involving hydrocarbons and sulfate and the reformation of reservoir should be two closely related and dependent processes induced by whole TSR.