The application of bioaugmentation techniques in anaerobic fermentation was reviewed in term of mechanisms, effects and influencing factors of the bioaugmentation process. It reveals that bioaugmentation has positive effects on anaerobic fermentation, such as in feedstock pretreatment, anaerobic digestion processes start up and biogas produce. However, most of the existing researches were conducted in laboratory scale and batch assays. The focal point of bioaugmentation process is the survival and activity of functional microorganisms in the fermentation system. There are still a series of problems that need to be solved to increase the success of bioaugmentation strategies widely using in actual engineering, such as revealing the interrelationship of the inoculated microbial culture and existing microflora, developing stable and adaptable functional microbial agents, seeking better ways of bioaugmentation performance, establishing evaluation criteria of the bioaugmentation effects.