Abstract: In view of problem that open-channel flowmeter ca't work normally because mine water contains impurities of coal powder and sediment which deposit on surface of probe of open-channel flowmeter, a mine-used ultrasonic open-channel flowmeter based on M-Bus was designed. The flowmeter is composed of water-level weir slot and intelligent ultrasonic flow sensor, which can get formula between real-time flow and measured height of water head by water-level weir slot and calculate real-time flow by intelligent ultrasonic flow sensor to measure height of water head. The actual application showed that the flowmeter has advantages of accurate measurement, high reliability and simple operation.