Abstract:Kefir is a low-alcohol sparkling fermented beverage with acidic taste, contributing health benefits like intestinal microbiota regulation, antioxidant activities and hypolipidemic effect to consumers. Kefir is produced using kefir grain which functions as a starter in the process of fermentation. Kefir can be divided into two groups according to different fermentation substrates: water kefir and milk kefir. Water kefir is fermented by water kefir grains using a sugar-containing aqueous solution or fruit and vegetable juice as the substrate, while milk kefir is mainly made from milk, goat milk, camel milk fermented by milk kefir grains. Compared to milk kefir, water kefir has a shorter history of consumption, while diverse fermentation substrates and multiple health benefits, it has also received widespread attention from lactose intolerant people and vegetarians. However, there is scarce research on water kefir, which impedes the further improvement of production and processing technology. Starting from the differences between milk kefir and water kefir, this review focuses on the microbial diversity, functional traits and applications of water kefir, aiming to provide basis for the further research and development of water kefir.