The ultrasonic guided wave temperature sensor is currently an emerging temperature measuring instrument in the industrial field, and the selection of its guided wave has important impact on the performance of the sensor. Magnetostrictive torsional wave is suitable for the application, as the basis for temperature measurement with its wave speed proportional to the temperature as well as the characteristics of low decay and easily pick-up. In this article, the magnetostrictive material Fe83Ga17 wire is selected to generate and conduct magnetostrictive torsional waves. The relationship between the flight time and temperature of the torsional wave at a fixed distance is calculated to achieve the fitting relationship between the wave velocity and temperature. According to the fitting relationship and the measured torsional wave velocity, the temperature measurement is realized, and an output voltage model based on a magnetostrictive torsional wave temperature sensor is proposed. In experiments, the output voltage of the magnetostrictive temperature sensor reaches 215. 7~ 465. 2 mV under the room temperature up to 500℃ . The fitting relationship between the measured temperature and the wave velocity can be used as a basis for temperature measurement. To increase the upper temperature measurement limit of the temperature sensor, Fe83Ga17 wire is coupled with the heat sensitive material Ni 20Cr80 wire into a new waveguide wire, and the temperature sensor after structural optimization is obtained. The unamplified output voltage of the optimized sensor reaches 44. 9~85. 6 mV under the temperature from room temperature up to 1 200℃ . The wave speed of the torsion wave remains highly proportional to the temperature in the temperature region, which is capable for reliable temperature measurement under 1 200℃ .