Abstract: Space environment simulation test equipment falls within the scope of a large container. In order to ensure the sealing performance of large space environmental simulation test equipment,like all large container,leak detection only in equipment processing stage or after the installation is not enough. Leak detection of the large space environmental simulation test equipment is necessary throughout the design of equipment,spare parts processing,equipment installation and debugging stages,and we put forward the specific content of leak detection in different stages of the work. Leak detection for this equipment mainly USES the helium mass spectrometer leak detection technology,such as injection method,vacuum leak detection method and the helium method,etc. Aiming at the problem of insufficient sensitivity in a large container leak detection,the total leakage rate test of vacuum chamber accumulation method was proposed,and introduces the testing steps in detail.