Abstract: Theaflavins were pigments which were originally found in the black tea, they possess a benzotropolone skeleton formed during black tea fermentation from co-oxidation of selected pairs of catechins. The content of theaflavins was an important indicator of black tea's quality, due to the function that they are able to significantly improve the color and taste of infusion. Besides, theaflavins possesses multiple beneficial bioactivities, such as the anti-oxidation, anti-bacteria, anti-inflammatory, cancer chemopreventive action and cardiovascular protection activities. In this paper, the bioactivities and the mechanism of theaflavins were summarized.