Abstract: Two consecutive landslides occurred in October 10 and November 3, 2018 at Baige on the border of Sichuan Province and Tibet Autonomous Region and caused barrier lakes on the Jinsha River. In accordance with the unified arrangements of Ministry of Water Resources, Changjiang Water Resources Commission timely started the emergency response mechanism, scientifically analyzed the flood risk of the dammed lake, studied the structural treatment scheme in advance, and reasonably regulated the reservoirs on the middle stream of the Jinsha River, providing powerful technical support for the risk treatment of the dammed lakes. This paper gives a detail introduction to routing process of the dam breaking flood and the 4 cascade reservoir emptying schemes before and after "11.3" barrier lake breaking. By using the reservoirs of Liyuan, A'hai, Jin'anqiao to retain flood, the cascade reservoirs on the middle stream of the Jinsha River emptied 1.3 billion m3 capacity for impounding the dammed lake breaking flood, which reduced the 10000-years flood of the Jinsha River to 1000-years flood and ensured the safety of downstream reservoirs, successfuly treated the risk of the dammed lake.