Saponins are a class of glycoside compounds whose aglycones are triterpenoids or spirostanes, widely exist in a variety of Chinese herbs. Saponins are one of the important active components of medicinal plants and have a wide range of bioactivities. In order to promote the better development and utilization of saponins, the process of digestion, absorption and metabolism of saponins in vivo was reviewed in this paper. At the same time, the main bioactivities of common saponins and their potential mechanisms for alleviating diseases were summarized. Finally, the potential of saponins as functional food has been pointed out, and microbial transformation can make saponins better play this potential in the future.