Abstract: The mass spectrometer leak detecting technology has such advantages as high sensitivity,speed reaction and good adaptation,it can satisfy the requirements of leak detection of the complicated equipment in the space engineering.The different leak detecting technologies are used in the fields as ground environmental simulation experiment equipment,liquid rocket,satellite_borne instruments,vehicle and railway LH 2 tank.The problems of leakage in space equipment have been dissolved.The quality of space products is assured.It is proved through practice that the mass spectrometer leak detecting technology will have the great prospects in China space industry.