The invention relates to an urban waterlogging monitoring and pre-warning system and pre-warning method. The urban waterlogging monitoring and pre-warning system comprises a processing unit, a surfacerunoff water depth monitoring unit, an underground drainage network monitoring unit, a meteorological information monitoring unit, a rainfall monitoring unit, a communication unit and a drainage unit, wherein the surface runoff water depth monitoring unit is electrically connected with the processing unit; and the processing unit is suitable for judging the urban waterlogging condition accordingto the actual surface runoff flow of various monitoring points, an excess surface water depth, an underground drainage network drainage state, weather information and rainfall, and uploading the urbanwaterlogging condition to a server through the communication unit in real time, and controlling the drainage unit to drain water when the processing unit judges urban waterlogging. According to the urban waterlogging monitoring and pre-warning system and the pre-warning method, analysis and statistics are carried out by comprehensively transmitting and processing monitoring data and combining bigdata with deep learning artificial intelligence, early prewarning information is issued, processing planning measures are generated in advance and intelligent control is implemented on electrical equipment at various sites.