Abstract: This paper presents seven types of biological hydrogen production systems and the mechanism，affecting factors，methods of enhancement of hydrogen production as well as research progress. The recent studies are focused on photo fermentation and anaerobic fermentation technology. Anaerobic fermentation systems have the great potential to be developed as practical biological hydrogen systems due to its high hydrogen yield. A hybrid system using photosynthesis and fermentative bacteria can enhance the hydrogen production and reduce the need for light. The process will be the future direction of biological hydrogen production.