In order to measure the temperature parameters accurately in the flight test of aircraft load spectrum, a strain decoupled and sensitizing fiber Bragg grating (FBG) temperature sensor is designed. The new structure sensor is designed through mechanical modeling analysis, the sensor's FBG is sensitized, and aluminum 7075-T6 is selected as the substrate for full-coverage packaging. The indirect contact between the packaging position of FBG and the structure part is proposed to eliminate the influence of structural deformation on the temperature sensor. The temperature sensitive speed of the calibrated test sensor is 40.4 pm /℃, which is 4 times that of the ordinary fiber grating. Then, the test system is built to explore the performance and the decoupling characteristics are verified on the tensile testing machine. The deformation of the tensile test piece has no influence on the temperature sensor, which is consistent with the theoretical analysis. Finally, sensors are attached to the aircraft cockpit for practical engineering applications. The experimental results show that the maximum temperature difference measured by the sensors is no more than±1℃, which meets the requirements for accurate measurement of temperature parameters in the actual flight test of the aircraft load spectrums and allows the sensor to be used for actual temperature measurement.