To address the issue of uneven gas flow velocity distribution upstream of natural gas pipeline flow meters, a wave-type fin flow conditioner was designed. The Computational Fluid Dynamics (CFD) numerical simulation method was used to analyze the velocity distribution inside the pipe, and the rectification effect of the flow conditioner was measured by using the offset degree and the minimum length of the straight pipe section. The offset degree at a specific downstream section was calculated when the fluid passed through a 90 degrees elbow spoiler component without a flow conditioner with an Etoile conditioner and wave-type flow conditioner. The results show that the wave-type flow conditioner has a better rectification effect, and the minimum straight pipe section length is shortened by 72% compared to without a flow conditioner, greatly reducing the pipeline design cost and improving the accuracy of measurement of the Ultrasonic flowmeter.