Abstract: Soap film flowmeter is an important measuring instrument for environmental monitoring. In order to meet the effective traceability of micro gas flow in low-pressure test of flow meter for environmental monitoring, reduce the impact of gas humidity on the accurate measurement of soap film flowmeter, and improve the reliability of micro gas flow value transmission. In this paper, the operating characteristics of soap film flowmeter are analyzed, and the calculation method of humidity correction for micro gas flow is given. The results show that the humidity correction calculation method can effectively reduce the influence of humidity on the metering characteristics of soap film flowmeter.