A semiconductor absorption fiber-optic temperature sensor was designed for aircraft. The sensor was based on the temperature dependence of the band edge absorption of infrared light in GaAs semiconductor platelets. The sensor used GaAs chip as the sensitive element of temperature,and the optical fiber was medium of transmitted light,and the diode is the light source,and the triode is a transducer of photo-electricity. The twin-channel compensative measure system can eliminate the influence of light source fluctuation. In addition,the temperature sensor had many more advantages such as small in volume,simple in structure,high in sensitivity and resisting strong electromagnetic interference. According to the experiment,the sensor has accuracy of 0.1℃ over a temperature rang from-20℃ to 85℃. It was suitable for measuring the environment temperature of the aircraft in strong electromagnetic interference. It was the base of achieving the temperature measurement further in optic transmission and craft controlling system.