The flood of the Yangtze River has the characteristics of high peak, large quantity and long duration. The Yangtze River Hydrology Bureau summarizes and combs the complete business process chain of flood hydrological monitoring, and gradually constructs the Yangtze River flood hydrological monitoring system. Including station network layout, early warning response, monitoring technology, information processing, results output and other dimensions. The hydrological monitoring system of the Yangtze River flood has been gradually constructed and has been successfully applied in many flood basins. Especially under the special situation of COVID-19 epidemic situation in 2020 and the severe flood situation in the Yangtze River Basin, the scientific and practical nature and practicability of the hydrological monitoring system of the Yangtze River flood are further verified. In view of the shortcomings existing in the existing monitoring system, this paper looks forward to the frontier technologies involved in flood monitoring, and has a certain reference function for flood hydrological emergency monitoring.