Infrared/passive millimeter wave (IR/PMMW) combined guidance is currently the hot trend in the field of multi-mode combined guidance technology.The penetrability of infrared detection system under low visibility conditions is not as good as that of passive millimeter wave,while the passive millimeter wave detection image is not as good as infrared image in resolution.In order to better identify the target,a new method was proposed.Firstly,IR/PMMW image was de-noised by using the de-noising method of combing multi-wavelet packet with neighborhood average,and then multiple similar IR/PMMW images were obtained by using the multi-wavelet packet method,which were then fused with principal component analysis,and accurate histogram specification was conducted.Finally,according to the particularity of PMMW image,a region based image quality evaluation method was proposed.The experimental simulation results indicate that after processing with the new method,the definition of image is improved,and its easier to identify the target information.