：In this paper, the principle of distortion spectrum signal generation of the calibration device for the aircraft DC power supply characteristic testing system is introduced. According to JJF 1059-1999 "Measurement Uncertainty Evaluation and Representation", the uncertainty sources of the DC voltage distortion spectrum of the calibration system for the DC power supply characteristic testing device were analyzed, and the uncertainty evaluation method was given. Finally, according to the above-mentioned uncertainty evaluation method, the uncertainty of the DC voltage distortion spectrum of the DC power supply characteristic calibration device was evaluated.