This paper studies the period verification method for the PG7601 gas piston gauges, and elaborates the period verification method from the aspects of selecting the verification standards, determining the verification parameters, processing the verification data and analyzing the verification results. Unlike a single verification of pressure value， this method not only checks whether the pressure value is accurate and reliable, but also checks the working state of PG7601 more effectively and accurately by checking the effective area of the piston. The absolute value of the pressure error of PG7601 at each gas pressure test point is calculated and compared with the square and root of the expanded uncertainty of the two piston pressure gauges at the corresponding points. This period verification method provides a more scientific and effective way to check the working state of gas piston gauges.