The influence of laser jamming on CCD imaging system is introduced. The similarity between laser jamming image and background clutter is illuminated in the view of their influence on electro-optical imaging detection system. Aiming at the frequency characteristic of laser jamming image and combining with background clutter metrics in machine vision, a comprehensive image metric for describing laser jamming effect is proposed by taking advantage of the predominance of wavelet analysis, based on wavelet energy and spot size. The wavelet analysis on typical laser jamming images indicates that the approximation coefficients and detail coefficients will both increase with the raise of laser power; the laser spot in jamming image can be regarded as the approximation coefficients, and the laser speckle around the spot can be seen as detail coefficients, which is similar to the salt noise. Laser jamming experiment in the field of view and simulative calculation show that laser jamming can reduce the segmentation accuracy of Otsu method, and raise the false alarm probability of correlation method. The metric can avoid the weaknesses of spot metric and wavelet energy metric. Hence, it is able to reflect the performance of laser jamming on CCD imaging system in the field of view properly.