Abstract: The online flow data of river sections is of great significance for water works regulation and flood warning and forecasting. Some hydrological stations are limited by terrain and river navigation, and cannot install flow measurement cable channels, which poses problems such as time-consuming and laborious flow measurement, and high risk of flow measurement during major flood periods. A study was conducted on the application of online H-ADCP flow monitoring system at Renhua Hydrological Station (hereinafter referred to as Renhua Station), and the flow measurement principle of H-ADCP was introduced. The calibration analysis of the average flow velocity of the cross-section calculated by the measured flow rate and the representative flow velocity measured by the online equipment was used to obtain the calibration relationship between the average flow velocity of the cross-section calculated by the representative flow velocity of Renhua Station. Based on this, the cross-section flow rate was calculated and compared with the measured flow rate and flow process. It was found that online H-ADCP has good measurement accuracy at Renhua Station and meets the requirements of hydrological testing. The application of H-ADCP at Renhua Station has improved the online monitoring level of flow in the Jinjiang river and Renhua County areas, and also provided experience and reference for the intelligent monitoring, digital compiling, and modern management of smart hydrological stations in future smart systems in water sector.