Résumé : Various anaerobic environments exist in the Earth’s ecosystem, which can produce a great deal of organic matter each year. In anaerobic habitats, bacterial sulfate reduction may occur due to the action of sulfate-reducing bacteria. As a result, hydrogen sulfide (H2S) is formed. This paper focuses on sulfatereducing bacteria and the revision of the activity characteristics of these bacteria in the reducing environment. It discusses the metabolic process of sulfate-reducing bacteria using sulphate and organosulfur compounds as sulfur source, the mechanism of bacterial sulfate reduction and H2S formation mechanism. There are two main ways of H2S formation in sulfate-reducing bacteria, the production of metabolic sulphate and the metabolic organo-sulfur compounds (mainly cysteine). The paper, combined with the activity characteristics of sulfate-reducing bacteria and the pathway of metabolic formation of H2S, also discusses the circulation of sulfur in the environmental system of the Earth due to the action of sulfate-reducing bacteria, concerning the redox zone division in submarine sedimentary strata and landfills, the biogas formation phase of sulfate-reducing bacteria metabolism in sedimentary formations, and the bacterial sulfate reduction action in salt lakes (seawater) systems. Moreover, the production of hydrogen sulfide and the formation model of dolomite are both presented here. The findings support that sulfate-reducing bacteria are the most important biological source of H2S production. The study of the physiological characteristics of sulfate-reducing bacteria and the formation mechanism of H2S due to bacterial sulfate reduction can provide useful reference for the exploration of the laws of sulfur geochemical cycle and the rules of the ecological environment, which is essential for the protection of the natural environment and the restoration of polluted ecosystems, and can also provide a useful reference for the control of aerobic microorganisms.