Abstract: Regular calibration is a necessary task to maintain the performance of measuring instruments. The calibration environment of gas flowmeters should be as consistent as possible with the actual working conditions. In order to accurately verify the actual performance of gas flowmeters, an air circulation standard facility has been developed, in which pressure and temperature can be precisely controlled to meet different calibration requirements. In this air circulation system, the gas temperature can be adjusted within the range of 15℃～30℃, with a deviation controlled within ±0.2 ℃. The proposed system is suitable for gas flowrates ranging from 5 to 2500 m³/h, with adjustable pressure ranges of (0.1～2.0) MPa. The best uncertainty of the standard facility is 0.26% (k=2), which can meet the calibration requirements of various medium and high pressure gas flowmeters under different working conditions.