The temperature is a main factor to affect the performance of the FOG, especially to the high precision FOG. The paper obtains from the experiment which was separately completed under the normal temperature, the low temperature and the high temperature three conditions. Using the thermistor separately to carry on the monitor to the top six important spot temperatures, output curve, the zero-bias change curve, the temperature variation curve of the optical fiber unloading to the stable were obtained. After analyzing the output curve, the zero-bias change curve and the temperature variation curve, some discoveries are found that not only optical fiber gyro own thermal reaction can affect the optical fiber ring, moreover the ambient temperature change also can have the influence to the optical fiber ring. According to this phenomenon, it is experimental proved that temperature control is an effective way to improve the FOG output characteristic.