Abstract: The theoretical and experimental studies about the effect of air capacity and air resistance in the air purge method were carried out. The results show that the air capacity and air resistance have obvious attenuation effect on the pressure amplitude but little effect on the phase position of the pressure wave. The attenuation effect increases with the air capacity volume increasing or the air resistance diameter decreasing. The attenuation effect of the air capacity and air resistance combination is bigger than that of a single air capacity or a single air resistance. The combination attenuation effect is bigger when the air resistance is before the air capacity. The air capacity and air resistance have little effect on the air velocity at the entrance of the purge tube and thus have no effect on the design of the purge cup. The theoretical and experimental results in this article provide fundamental for the design and application of the air capacity and air resistance in the air purge method.