Feed fermentation in rumen can cause the loss of energy and ammonia nitrogen, the reduction of animal performance, and the environment pollution. Saponin is a type of plant secondary metabolite, which contributes to the modulation of rumen fermentation. This paper reviewed the chemical structures, distribution and forms of saponins, as well as recent research advances on its effects on rumen fermentation and performance. The review can provide references for further researches on using saponins as additives in modulation of rumen fermentation in China.［Chinese Journal of Animal Nutrition, 2010，22（6）:1515-1522］