Abstract: The presence of liquid in the gas flow will cause a metering bias to the dry gas measurement system when it is used in wet gas flow metering. This paper analyses the factors affecting the metering accuracy of gas metering system in wet gas flow. The calculation bias of natural gas compressibility factor induced by the water vapor is investigated applying gas composition of the wet gas flow in an actual gas field. The wet gas measurement performance of orifice plate and ultrasonic flow meter under low liquid loading condition are evaluated based on theoretical analysis and experimental study respectively. This provides technical reference for custody transfer in the cooperation of gas and oil field and the standard formulation of wet gas measurement.