Abstract: Microbially mediated carbon cycles are the core component of biogeochemical element cyclingin hot spring ecosystem. Thus, the study of microbes and their metabolic mechamisms involved in carbon cycling in hot springs avails to reveal the origin and evolution of early life on Earth and to explore extraterrestrial life, and has great significance in bioengineering applications. Focus was given on the phylogenetic distribution of functional microorganisms involved in geothermal carbon cycling and their functional gene abundance, activity and composition in response to environmental factors (e.g., temperature, pH).This review aimsto understand the current situation of microbes driving carbon cycles in hot springs and provide theoretical basis for~futureresearch