Abstract: The main advantages and disadvantages of orifice flowmeter, V-cone flowmeter, precession vortex flowmeter and vortex street flowmeter are analyzed; the working principle of gas ultrasonic flowmeter in gas drainage pipeline is introduced, and the measurement system of gas ultrasonic flowmeter in gas drainage pipeline is designed; this paper focuses on the digital signal processing technology of gas ultrasonic flowmeter measurement system; the application of gas ultrasonic flowmeter in gas drainage and air pressure in coal mine is described in detail.