Abstract: In the AIT process of a spacecraft, the testing of the total leakage rate is usually conducted with the helium accumulation in an ambient pressure environment based on the mass spectrum technology. A spacecraft container is often used to collect the helium gas leaked out from the subsystem of the spacecraft. During the testing, the container might have a negative pressure which would cause damages of the structure. To prevent such damages, we must increase the weight of the spacecraft container, with and an overweight design to prevent such damages. In this paper, we propose a new method, that is, the helium accumulation under the positive pressure environment based on the mass spectrum technology to avoid any damage to the container. The theoretical analysis and the experimental verification show that the new method is applicable for the total leakage rate testing of the spacecraft, and can help a lightweight design of the spacecraft container.