Abstract: To improve the level of online monitoring in hydrological measurements, this study, based on the results of comparative measurement, calibration, verification, and analysis conducted on radar wave online flow measurement systems at 8 hydrological stations (including Shigu) in the Yangtze River Basin during 2018—2023, adopts classified indicators and methods of mathematical statistics to evaluate the application of the systems under different river types, hydrological conditions, radar equipment, and measurement environments. The results show that: (1). The radar wave online flow measurement system has high overall accuracy in flow measurement, and the rating accuracy of measurement events classified by flow level at each hydrological station meets the specification requirements. (2) For the rating curves that meet the rating accuracy requirements, the absolute value of the systematic error is within 0.6%. The random uncertainty of 5 hydrological stations is within 10%, while the accuracy of this indicator for the remaining 3 hydrological stations is relatively lower, within 15%. (3) The system has good application reliability, and the verification results are basically consistent with the rating accuracy: for the 5 hydrological stations with higher accuracy, the absolute value of relative error in over 80% of measurement events is within 5%; in contrast, for the 3 hydrological stations with lower accuracy, less than 50% of measurement events fall within this range. (4) Within a certain range of water level or flow, the system can basically meet the accuracy requirements for online flow monitoring at hydrological stations.