Based on the needs of the urban waterlogging monitoring and early warning in Shenzhen, an introduction is made to the design method of a water logging system, which consists of the high accuracy pressure and water level gauges and automatic weather stations at key points of the urban river, in the aspects of the system architecture, measurement principles, parameter setting, design error compensation, etc. The system adopts a set of data collected every minute, and the water level measurements have an accuracy of 01%. Through comparison with the measurements from national standard hydrological stations, it is found out that the water level measurements from the station are consistent with the astronomical tide water level fluctuation, with the phase being 1 hour lagged and the measurement error being less than 006 m. Through a case analysis, it is concluded that when the average area rainfall in the Maozhou River basin is greater than 40 mm and the measured water level reaches 15 m, and maintains more than four hours, the urban area is prone to waterlogging. The combination of water level measurements and the observed area rainfall help improve the capabilities of waterlogging early warning and forecasting for a city.