Abstract: Portable CD3 （Ａ） type pitot tube flowmeter is used to measure parameters such as gas flow, temperature, absolute pressure, flow rate and environmental barometric pressure in gas extraction pipeline of coal mine or gas transportation in natural gas, shale gas pipeline. The instrument is based on the pitot tube principle to research and design, and it can in measure, display, store and query parameters such as gas flow rate, flow velocity and pressure of medium, medium temperature, environmental barometric pressure in pipeline in real time, and can support data import and export, forward and reverse bi-directional measurement. The principle of flowmeter and the application of field adaptability are briefly described.