Abstract: The pressurization test of containment, which has the characteristics of high risk, complex process and long holding time, is one of the most important special projects during construction and operation period. For the sake of increasing the economy capacity units and saving the maintenance time, an effective approach is to increase the pressurization rate. However, the approach is likely to cause the increase of the stability time of air in containment and the decrease of the accuracy and reliability of the containment leakage test. Therefore, it is necessary to study the influence of the increase of pressurization rate on the stability of air. Taking the M310 reactor as an example, the theory of computational fluid dynamics was adopted to simulate the whole process of the pressurization test. When the rate of pressurization was 15 kPa/h and 40 kPa/h, the variation of the internal pressure, velocity and temperature of the containment was analyzed, and the influence of the pressurization rate on the stability of air in containment was investigated. It was shown by the results that if the rate of pressurization was raised to 40 kPa/h, the internal air of the containment was stable after reaching the test pressure for 4 h.