Polarization-maintaining fibers (PMF) are widely used in coherent optical communication systems, optical fiber sensors, optical fiber lasers, optical fiber gyros, and so on. The temperature stability is one of the key factors for the application of such fiber. In this paper, the characteristics of the fiber Bragg grating(FBG) fabricated in the PMF are analyzed by both of the theory and experiments. The results show that the higher of the temperature, the narrower of the polarization peak space. This is the theory basis of the high resolution new method to get the temperature characteristic of PMF. The experiments for the PMF at temperature range from -40 ℃ to 130 ℃ are measured, and the results agree well with the theory analysis.