To investigate and evaluate the jamming effect of broad-band camouflage on spectral imaging devices, camouflage jamming tests were carried out with a hyperspectral imager and a kind of broad-band camouflage net. The camouflage jamming effect on the hyperspectral imager was analyzed and evaluated quantitatively by using the mean absolute difference. The results show that the broad-band camouflage net has certain jamming effect on the hyperspectral imager at all the spectral bands, and the markedness of camouflage jamming effect varies with the target characteristics before being camouflaged, camouflage net layers and the spectral band. By using the mean-absolute-difference rule, camouflage jamming effect on spectral imaging could be evaluated quantitatively and impersonally, which makes the evaluation results more accurate. So the mean-absolute-difference rule could be used as a quantitative and impersonal rule for evaluating the jamming effect on spectral imaging.