A new dual-wavelength optic-fiber temperature sensor is introduced in this paper. Transmitted probe of this sensor system is designed. LED IR880 and LED IR940 which peak wavelength is 880nm and 950nm are used as the survey light source and the reference light source of the sensor system. So the infection from the changes of the optical fiber transmission loss, the temperature effect of the temperature probe and the optical detector excursion of the sensor can be eliminated. The accuracy and stability of the temperature sensor can be improved and the cost of temperature sensor can be reduced.