To satisfy the application of fiber grating sensor technology in high vacuum thermal environment, FBG on two different kind of sleeve compactly single model fiber covered by acrylate and polyimide were researched. Influence of the cover on the peak wavelength power of FBG in high vacuum thermal environment was analyzed and verified. Firstly, experimental program of influence on FBG reflection spectrum characteristics was designed and then a hardware-in-the-loop detection platform was set up. Finally, the influence of temperature and vacuum on the reflection peak power of FBG in different coating single-mode transmission fiber under high vacuum thermal environment was studied and verified. Experimental results indicated that: when vacuum varied from normal pressure to 10-4 Pa level and then return to normal pressure, temperature of two different coating single-mode transmission fiber dropped to -196 ℃ from room temperature and then returned to room temperature, after 224 hours, the peak power of the FBG reflectance spectrum did not change. It provides the theoretical and experimental basis for the application of optical fiber sensing technology in high vacuum (pressure about 10-4 Pa level) and thermal environment (-196-25 ℃ temperature cycle).