There are many gas sources in the Dewar’s vacuum insulation space, the biggest gas source is material outgassing. The problem of outgassing pollution caused by the desorption, volume diffusion, and penetration of the adsorbed gas on the inner surface of the vacuum insulated space of the refrigerated infrared focal plane detector Dewar component was focused, which affected the cool down time and restricted the service life of the infrared detector component. A passivation treatment plan for the inner surface of the infrared detector Dewar was designed, and the passivation film on the inner wall of the Dewar was prepared based on a certain type of Dewar product. The pressure rise method was used to compare the outgassing rate, and the gas composition was analyzed by a quadrupole mass spectrometer. The test results of outgassing rate show that the passivation film effectively inhibits the release of hydrogen, and the outgassing rate of Dewar is reduced by more than half. The processing method of the passivation film on the inner surface of the Dewar is simple and effective, which improves the vacuum life and has engineering promotion value.