Plant extracts contain saponins, alkaloids, essential oils, tannins, polysaccharides and other active ingre-dients. The plant extracts played a certain role in the rumen regulation of ruminants, including regulating VFA com-position of rumen fermentation, enhancing by-pass protein flow and reducing methane emission. The effects of sapo-nins, tannins and plant essential oils on the rumen fermentation and methane production of ruminants were summa-rized in the paper, so as to provide reference for the application of plant extracts in practical production.