Infrared radiometric calibration is a method for establishing a relationship between the digital quantization values of imaging spectra and the spectral radiance values of a target. Calibrating the measured spectra is crucial in quantitative analysis. In practical applications, because of the stability of the instrument and the effect of the target radiation characteristics on the instrument, the quality of calibration results cannot be evaluated effectively. This study proposes a method based on noise equivalent spectral radiance (NESR) to quantitatively analyze the accuracy of calibration results. A two-point linear radiometric calibration method is used to calibrate the instrument, and the measured NESR value is obtained using the NESR signal-to-noise ratio calculation method. By comparing the measured NESR with the nominal NESR parameter, the accuracy of the radiometric calibration results can be determined rapidly and quantitatively. Data obtained using a self-developed imaging telemetry system are used for verification, which demonstrates that the proposed method can rapidly and effectively evaluate the accuracy of radiometric calibration results, thereby improving the quality of brightness temperature spectra after calibration and establishing a foundation for subsequent infrared spectral gas identification.