The principle of fiber Bragg grating sensing is analyzed. Fiber Bragg grating(FBG) is placed in a thin metal tube and a special kind of high temperature-resistance pastern felts with two ends of the metal tube to make FBG not to fall off. Tensile force is put on the FBG by the screw thread in the process of encapsulation,which ensures the FBG tightening in changeable temperatures out of environment. It is found that the structure of FBG temperature sensor has good repeatability and linearity. The experimental results show that the temperature response sensitivity is 0.0252 nm/℃,and the response curve is linear,and the whole measuring range is over 200℃ at least. The FBG temperature sensor can be used in high temperature environment.