Abstract: Under the changing environment background of frequent extreme weather and rapid urbanization, urban waterlogging disasters have seriously troubled economic development of cities in China. In view of the increasingly serious impact of waterlogging disasters in Tianjin city, an automatic waterlogging monitoring and early warning system for Tianjin city is designed using internet and WebGIS technology. The system consists of three parts:automatic waterlogging monitoring subsystem, waterlogging monitoring and risk early warning service subsystem and waterlogging risk early warning push subsystem, which realized the functions of real-time monitoring of urban road waterlogging, historical query statistics, comprehensive data analysis, waterlogging risk early warning and location-based early warning information push at the mobile end. The system provides targeted early warning service products to government departments and the public, respectively; so as to improve the emergency response efficiency of various flood control departments and the public's ability to prevent and avoid disasters, and reduce casualties and property losses caused by urban waterlogging.