Abstract: Index of biotic integrity (IBI) is a quantitative one, often used to scale the abilities of aquatic biocoenoses to maintain species composition, diversity, structure and function stability. IBI has been gradually developing in the past 30 years and now into one of the most important indices to quantitatively assess aquatic ecological health. IBI is a numerical value, which is acquired by integrating a number of measuring indices different in sensitivity, and relies on ecology and mathematics as its theoretical foundation, and some other disciplines, too, like biology, environmental science, etc.. IBI being a quantitative analysis method, its theoretical and technical system keeps on developing and evolving and its key technical links lie in selecting reference sites, screening measuring indices, empowering and recombining the indices, for materialization of these links exists a variety of ideas and methods. Research on prediction models based on large volumes of monitoring data is a hot spot topic in the current international academia. However, little has been reported about the IBI prediction models in China. In addition to the traditional F-IBI (fish-based IBI), B-IBI (benthod-based IBI), A-IBI (sessile algae-based IBI), P-IBI (plankton-based IBI) and AP-IBI (aquatic plant-based IBI), some scholars have put forth M-IBI (microbe-based IBI). Based on the above-listed findings in the study on s-IBI (single group-based IBI), the study on m-IBI (multi-group-based IBI) will be an important target of future researches. The purposes of applying IBI can be described as quantitative analysis of water ecological health, quantitative analysis of responses of water ecology to human disturbances, and prediction of water ecological health. The authors hold that IBI can be characterized by quantitativeness, object dependence, interdisciplinarity, standardizing trend and systematic deviation, and that IBI is a promising method for ecological health assessment of rural rivers, irrigation districts and farmlands.