Abstract: Natural gas ultrasonic flowmeter is often used with the "regulating metering train" consisted of regulating valves in gas pipeline. High frequency noise was generated when mechanical energy was transferred to acoustic energy. The frequency is close to the working frequency of ultrasonic flowmeter, which severely impacts the normal working condition of ultrasonic flowmeter. Modified design revealed that the accuracy and stability of flowmeter were possibly reduced by the Gain and SNR of flowmeter in the non-metering condition, which are influenced by the installation position of regulating valve, the use of denoised type regulating valve and the installation of T-shaped joint. It is considered that adjusting the pressure metering procedure and the working condition of axial-flow regulating valve, adopting non-denoised type gas ultrasonic flowmeter, elongating the straight pipe length in the upstream and downstream of ultrasonic flowmeter and adding T-shaped joint along the reversal direction of gas flow can effectively eliminate the impact of high frequency noise on ultrasonic metering.