In order to strengthen the capacity-building of hydrology itself， in view of hydrologic measurement and forecasting，the hydrological system advance to make great efforts to research and apply new technologies，improve monitoring means and methods，and raise the level of hydrologic automation and intelligence.In this paper，take the application result of H-ADCP flow measurement online system in Nanchang Gangqian hydrological station as a case.The principle，performance of velocity measurement and flow measurement and the application examples，experience are stated，which can be used as a reference for the application of H-ADCP flow measurement online system in the hydrological stations of medium and small rivers.