A new fiber Bragg grating temperature sensor has been presented, which was made by fixing a fiber Bragg grating on a polymer substrate that has a large thermal expansion coefficient. The temperature sensitivity of this new fiber Bragg grating temperature sensor is about 82.69×10-6 /℃, which is 12.3 times of that of a nude fiber Bragg grating. The wavelengths of the light reflected from the fiber Bragg gratings were measured in the temperature range from -80 to 0 ℃. The low temperature characteristic of this new fiber Bragg grating temperature sensor was experimentally studied, and compared with that of a nude fiber Bragg grating and an Al substrate fiber Bragg grating. The temperature response characteristic of this new fiber Bragg grating temperature sensor is good.