In view of three flood and waterlog disasters in Shanghai located at tidal river network area,four numerical models of the rainstorm runoff model,the storm-surge model,the hydrodynamic model and the disaster evaluation model were developed.Moreover,based on GIS and above models,Shanghai Flood Prevention Aided Decision-making System has been set up aiming at real-time monitoring,analyzing,forecasting,evaluating and publishing to flood disasters.It can accurately,fast and conveniently provides information support for analyzing flood and waterlog regime,making flood prevention plans,evaluating flood disaster situation an d managing water project.This paper systematically expatiates on the system design,main modules,key technology and system characteristics,furthermore,application of GIS and numerical models in the system were introduced.