Anaerobic fermentation technology is a sustainable method for treating organic waste. However, the process can be hindered by low gas production, system instability due to acidification, ammonianitrogen inhibition, and microorganisms. The addition of biochar to the anaerobic fermentation system can improve gas production rates and maintain system stability. This paper summarizes the research progress on the effect of biochar on anaerobic fermentation systems by discussing the preparation and characteristics of biochar, its main effects on anaerobic fermentation systems, Exploring the potential for further research and in-depth application of biochar in anaerobic fermentation systems.