Abstract: Aojiang River,situated in the south of Wenzhou city in Zhejiang province,is struck by the flood disasters frequently.A system of flood forecasting and dispatching decision support system in Aojiang River Basin is developed to enhance the flood management and disaster mitigation measures. This essay mainly introduces the design,function modules,logical structure,model organization and the method of applying hydrological and hydraulics models in simulating flood movement in the watershed of the system. It aims at establishing a frame of flood forecasting and dispatching decision support systems that is suitable for middle and small watersheds in Zhejiang province and Southeast China border on the sea and even the whole country.