Aiming at the problem of low-temperature sensitivity of bare grating, a packaging method is designed and its structure is made. The design packaging mode is as follows: fiber Bragg grating (FBG) is placed in a capillary glass tube, filled with 353ND epoxy resin adhesive, and finally fixed on the copper substrate. In this paper, the mechanism of FBG temperature sensing and sensitization is analyzed theoretically, then the structure is designed and manufactured, and finally the temperature sensing test is carried out. The thermal expansion coefficient of polymer 353ND and copper sheet is significantly higher than that of bare grating, and additional stress is applied to the fiber grating when the external temperature changes, so as to improve its temperature sensitivity and protect the structure of FBG sensor. The experimental results show that the reflected wavelength of FBG maintains good linearity in the temperature sensing test from 40℃ to 140℃. The temperature sensitivity increases from 10 pm/℃ before sensitization to about 21 pm/℃, and the linearity of fitting curve of temperature sensing characteristics reaches more than 0996.