To effectively evaluate the risk of flood disaster induced by dike breach in the detention basin，a numerical model for flood routing analysis was established by taking Zhuhu detention basin in Poyang Lake area as a typical case.The flood routing process in Zhuhu detention basin was systematically simulated.The important inundate information，including the inundate area，inundate depth and velocity in Zhuhu detention basin under a historical maximum flood le vel was obtained.Based on the obtained inundate information，the damage of life，economic and ecological environment in the detention area caused by the dike-break flood were estimated，respectively.The research results can provide important theoretical basis for the risk assessment of dike-break flood disaster，classification of disaster levels in the detention basin，and formulation of evacuation and migration schemes of personnel and materials.