Abstract: To achieve the accurate measurement of underground open channel flow,a new kind of array capacitance flowmeter is introduced in this paper.The self-designed array electrode capacitance sensor can realize double interface measurement of sludge thickness and height of water head.Through the use of the capacitance / voltage signal conversion chip CAV444,a simple,accurate measurement of capacitance is achieved.The sensor is high precision,easy to install and high performance price ratio,etc.