Abstract: It is bound to be a trend in flood control and hazard mitigation that the study object of flood disaster risk converts from single risk to integrated risk. So, the constitution characteristics analysis of integrated risk for flood disaster is the allimportant role. At first, by applying the theory on Disaster Science，the macroconstitution of integrated risk for flood disaster, which is composed of the hazard of flood, absoluteness in frangibility of environment, relativity in vulnerability of disaster carrier and evaluation for the situation of a disaster loss for the sake of macroevaluation for flood disaster risk, is presented. The corresponding quantitative approaches of them are constructed too. Second, from the point of view of model, the microconstruction of the risk chain, which consists of flood risk, engineering risk, investment risk, floodplain risk, flood ecoenvironment risk and decisionmaking risk for flood control, is structured regarding flood as the center. The corresponding quantitative conceptual model are constructed by Probability Theory. Besides, systemic analysis on the constitution of integrated risk has been carried through in the end.

Key words: flood disaster, integrated risk, risk constitution, macrostructure, microstructure