Online flow measurement system and measurement method

The invention discloses an online flow measurement system and a measurement method. The online flow measurement system comprises stand columns located on the two sides of a river, pulleys are arranged on the stand columns, steel wire ropes are arranged on the pulleys, hooks are arranged on the steel wire ropes, the pulley on one side of the river is driven by a direct-current motor, a winch is further arranged on the stand columns, and a pull wire of the winch penetrates through the hooks and then is connected with a rotor flow meter. A radar water level gauge is arranged above one side of a river, and the radar water level gauge, the rotor flow meter, the direct-current motor and the winch are all electrically connected with a PLC in the control box. Modern technologies such as the radar water level gauge, data acquisition, modern communication and information analysis are closely combined with hydrological flow measurement requirements; the hydrological flow online measuring and reporting device is efficien