The jamming result assessment factors of multispectral imaging reconnaissance equipments are analyzed. According to the correlation of spectral character curvilinear composed by the different channels of multispectral imaging reconnaissance equipments on the gray value of the same pixel, the identify probability to the target is calculated. Based on the identification probability ratio of multichannel spectral imaging equipments to the target before and after jamming, a jamming effectiveness evaluation criterion on multispectral imaging reconnaissance equipments is presented, which can be used to evaluate the jamming effect.