In order to know the change and the response mechanism of riparian vegetation to hydroelectric dams, three diversion-type stations on the following mountain rivers, Manyue River, Xiaoyuan River and Baili River, were studied. Plants were investigated in consecutive 1 m2 along three separate 12-m-long belt transects that were selected along every 100 m upstream and downstream sections of these rivers. The results showed that, first, 125 plant species that consist of 14 trees, 30 shrubs and 81 herbs in a total of 216 quadrats were recorded. Second, there were significant differences on plant communities (species richness, species cover) amongst rivers, which can also be found in terms of the upstream versus downstream. This suggested that the dams had resulted in changes in riparian plant communities, but differences caused by reservoir were within the natural range of variation found across the rivers. Third, we found the number of some xerophytes and highland plants, such as Cupressus funebris, is significantly increased in downstream of dams and some species that adaptated to tranquil reaches and lakes largely increased in upstream of the dams, such as Azolla imbircata and Polygonum nepalense. This revealed that the construction of dams had changed the riparian habitat, the composition and diversity of riparian plants between downstream and upstream of dams. Integrated operation and management of the whole basin should be taken for the health of river system. Copyright © 2013 John Wiley & Sons, Ltd.