Abstract: Reservoir flood forecast is one of the important contents of reservoir non-engineering flood control measures,which provides a large security guarantee for flood control,operation and management,rational utilization of water resources and industrial and agricultural production within the reservoir protection scope.Based on the comprehensive analysis of the rain water situation prediction of Shimantan reservoir and the principle of current reservoir application,a reservoir flood forecast model is established,and the method and programming skills of realizing reservoir flood forecast by Visual Basic 2015 are discussed.