As one of the important water-treatment methods in aquaculture, microorganism suspended growth means that microorganisms for water treatment grow in the water in a suspended way. This paper reviews the application process of microorganism suspended growth water-treatment system in industrial aquaculture, and summarizes the progress of its application. According to the analysis of literatures, animals cultured with biofloc in-situ aquaculture technology and microorganisms subject to water treatment grow in the same space, which is a widely used form of microorganism suspended growth at present and has the advantages of regulating water quality and providing bait, but it also has the disadvantages of high concentration of suspended solids. Thus, the ex-situ reactor with which the animals cultured are separated from the microorganisms subject to water treatment in space is used for treatment of pollutants and as a key water-treatment device of recirculating aquaculture system (RAS). The research shows that using the ex-situ reactor as the key water-treatment device of RAS can simplify the equipment composition and treat various pollutants as resources. It is still necessary to optimize to the process continuously and study the accumulation and flow of substances other than nitrogen and phosphorus during the long-term reuse of aquaculture water.