To study the impact of the evolution process of flood disaster on the resident lives and socio-economic development in the watershed, the evolution risk of flood disaster chain was evaluated from the perspective of disaster chain and complex network. By collecting typical cases of flood disaster and combining event tree analysis, the evolution network of flood disaster chain was constructed. Based on the Bayesian network and network propagation model, a flood disaster chain risk assessment model was built, and a case study was conducted in the Qinhuai River Basin. The results show that the comprehensive risk of flood disaster chain is composed of the accumulation or superposition of node risks. The comprehensive risk level of the “2016·7” flood disaster chain in the Qinhuai River Basin reaches the maximum value about 103 h after the occurrence of the flood disaster and the second peak value about 173 h, which is about 7 times the risk of primary flood disaster. Road accident, water supply and drainage accident, ecological environment damage accident, and water pollution accident are key nodes. Flood disaster→soil erosion disaster→water pollution accident→ecological environment destruction is the key transmission edge. By strengthening monitoring and response to key nodes and intercepting critical chains, effective disaster reduction and damage reduction can be achieved. Keywords: flood disaster; disaster chain; complex network; event tree analysis; Bayesian network; the Qinhuai River Basin 〖FL