In this paper,a fiber Bragg grating (FBG) temperature sensor and its packaging method for monitoring temperature of aerospace systems is presented.The mech anical structure of FBG temperature sensors is analyzed by mechanics simulation.On the basis of mec hanics simulation and theoretical analysis,the influence of FBG pre-stretching amplit ude and low melted point glass thickness on the stability of the FBG temperature sensors is discussed.The packaging method of the FBG temperature sensors is optimized,and the characteristic of FBG temperature sens ors is verified through the experiments.Four stability experiments are conclucted for the encapsulated F BG sensor,which are separated by twenty days.The experimental results s how that the standard deviation of the FBG sensor wavelength at all temperature points (including －70℃,－60℃,…20℃ and 30℃) is less than 0.57pm,the temperature sensitivity is 8.4pm/℃,and the standard deviation o f temperature measurement is less than 0.067℃.When the FBG temperature sensor is placed in the liquid nitrogen, the standard deviation of the FBG temperature sensor wavelength is 0.43pm in s ix days.In conclusion, the FBG temperature sensors possess excellent low-temperature stability.