In order to study the thermal effect on spectral- line shift of aerial imaging spectrometer, the characteristics, mechanism and manifestation of the instrument temperature load airbrone environment are analyzed, and the spectral-line shift characteristics of the spectrometer are studied. According to the characteristics of the temperature load in airbrone environment, the finite element method is taken to calculate the deformation and rigid body displacement of the mirror of the optical system at a temperature load, combined with the least squares method and coordinate transformation method. Ray tracing to the deformed optical system are carried out and its spectral-line shift characteristics are studied. The thermal-optical test and calibration test during flight is taken to prove the theoretical analysis. The results show that within the range of ±10 ℃, there is only shifting in the spectral direction, no tension or compression effects. During the calibration test of flight, the average line offset is 0.248 nm, satisfies the need of 1/3 of the accuracy (calibration accuracy is 1 nm). No further spectral calibration or correction is needed in the later imaging.