Abstract: Based on the original design closure scheme,physical model test and numerical simulation of river closure for TB Hydropower Station in Lancang River are carried out,the particle size and intensity of dumping material required for closure under different test cases are determined,and the recommended scheme of closure is put forward. Due to the poor diversion conditions of the diversion tunnel during the actual closure construction,it can be seen from the numerical simulation analysis that the closure difficulty is greatly increased under different discharge flows of the upstream power station. TB hydropower station and upstream power station belong to the same basin cascade company.The shutdown and discharge control of the upper power station can reduce discharge,reduce the difficulty of the closure to the maximum extent,and ensure the smooth implementation of the closure. The research results show that the analysis method combining model test and numerical simulation can provide a scientific decision-making basis for the implementation of the closure project,and cooperate with the“control discharge and assist in closure”mode of the upstream and downstream power stations in the cascade development of the river basin,which serves as a reference for the design and implementation of similar projects.