Study of epiphytic diatoms as bio-indicators spanned a century. By screening the research findings on the good indication of diatoms in Springer, Elsevier, and China National Knowledge Infrastructure, it can be grouped into aquatic environment variables, diatom index, ecotoxicology, paleo-environmental & paleo-climate, land use and eco-hydrological in accordance with the characteristics of the variables. Numerous studies certified that diatoms community and individual species have a good indication, based on species distribution and individual characteristics, especially in indicating the water environment and the ancient environment.