Flood disaster becomes an important issue that can cause harm, even the threats to human life the prone. The danger posed depends on the ability to prevent or anticipate the precipitation of the floods so that community readiness is very important in facing the threat of flood disaster. In order to know the level of vulnerabilities or potential flood disaster in the area of the prone flood, we develop a flood early warning system using Analytical Hierarchy Process (AHP). One of the approaches to combining the condition of rainfall, water level and flow rate in AHP analysis is to produce a prediction of the flood disaster. The use of the Internet of Things (IoT) technology is combined with mobile applications, which provide the information about warning flood for the public in real time