Abstract: With the maturity of gas ultrasonic flowmeter technology, the requirements of domestic and foreign standards for pipeline configuration have experienced several changes. In order to study the influence of different pipeline configurations on the metering performance of small diameter ultrasonic flowmeter, and to study the applicability of straight pipe length recommended in the standard to different types of ultrasonic flowmeter under complex process conditions, test experiments were carried out between DN100 ultrasonic flowmeter and standard device under different pipeline configurations. The results show that it has no obvious impact on the flowmeter performance by further shortening the length of upstream straight pipe to 20D on the basis of 30D after installing the flow regulator. When the length of straight pipe continues to be shortened, the maximum deviation of the flowmeter will be up to 1.5%. The experiments reflect the influence degree of the length of straight pipe on the metering performance, which can provide a reference for the performance evaluation of medium and low pressure trade transfer stations using small diameter ultrasonic flowmeter.