At present, it is generally believed that biological sulfate-reducing (BSR), thermochemical sulfate reduction (TSR) and thermal cracking of sulfocompound are the main causes of H2S in natural gas reservoirs. In addition, thermochemical sulfate reduction was thought to be the reason of reservoir with high content of H2S. This paper summarizes the research progress on hydrogen sulfide genesis and existing issues at home and abroad, so that the hydrogen sulfide reservoirs could be more concerned.