Abstract: In order to understanding the status of fish diversity in the upper Renhe River, field investigations were conducted during the period from 2016 to 2018 at 18 sampling sites. Specimens were collected by electro-fishing covering different habitat unit. A total of 36 fish species, including 34 natives and 2 exotics, was collected. Among these species, Leptobotia hansuiensis and Metahomaloptera omeiensis have been listed as the key protected fishes of Chongqing municipality, Scaphesthes macrolepis, Schizothorax prenanti and Pseudobagrus pratti have been listed as vulnerable by Red list of China’s Vertebrates. Small-sized and lotic species, such as Phoxinus oxycephalus, Gnathopogon herzensteini, Zacco platypus and M. omeiensis, distributed wildly in the upper Renhe river. Fish assemblages were mainly dominated by Phoxinus oxycephalus and other small-sized and lotic species. Species richness increased with the longitudinal gradient. Compared to the historical data, fish resources in the upper Renhe River have been declined seriously. Firstly, the number of fish species decreased dramatically. Secondly, the distribution range of some sensitive species reduced obviously. Thirdly, the miniaturization trend of some commercial targets was still serious. In order to effectively protect the fish diversity in the upper Renhe River, controlling the development of hydropower, reinforcing the fishery management and strengthening the scientific research were suggested.