Abstract: From November in 2011 to May in 2012，fish species composition and fish fauna in the lower reach of Yalu River were studied. The results showed that：a total of 33 species were collected，the most species-rich orders were Cypriniformes（12 species） and Perciformes（8 species）. The composition of fish fauna is relatively complex，native fish，temperate water fish，and fish lived in a steady water or the slow water were dominant；the fish in the lower reach of Yalu River belong to different ecological types in migration，water temperature tolerance and feeding habit. The fish community type in Dandong reach of Yalu River was the type of eatuary fishery community. The fish germplasm resources were precious，so it is necessary for us to further strengthen the protection of the ecological environment，pay attention to water pollution in the lower reach of Yalu River.