As a kind of anthropogenic activity with significant impact on river ecosystem, dam construction and reservoir creation will result in the degradation and disappearance of terrestrial ecosystem in its flooded area. It will cause the significant change of downstream eco-environment and disrupt the continuity and connectivity of natural rivers. There may be “accumulative effects” on the impact of river cascading development on its ecosystems, which is to “amplify” the impact of damming on river ecosystems step by step. However, the role, approach, and hydro-ecological mechanisms of the “accumulation effect” are still not clear. Additionally, this will also result in the uncertainty in the objective, targets, spatio-temporal scope and action path of adaptive management of river cascading development. In river cascading development, the current adaptive practice on restoring natural hydrological processes and river ecosystem may no longer be effective. There is need to understand the function and structure of river-reservoir system and its succession. The trade-offs between multi-stakeholders of river-reservoir system shall be also taken into consideration. The upper Yangtze River has experienced intensive cascading development, which is unique among the world’s rivers and will profoundly change the ecosystem in the upper Yangtze. The adaptive management of upper Yangtze should aim at optimizing the ecological structure of rivers and reservoirs and maintaining the health of river-reservoir ecosystems. Future research could be focused on the role and form of “accumulative effects” in upper Yangtze, and the trade-offs among multiple stakeholders. These will construct a new paradigm for the operation and management of green hydropower in the upper Yangtze.