Fusion method of subdivision band images of mid-wave infrared is presented based on both morphology processing and wavelet packet transform. Local fusion of two subdivision band MWIR images is implemented with morphologic erosion and dilation processing and weighted stacking method in order to eliminate saturating regions in the first subdivision band image that are done by sun irradiation. And global fusion between local fused image and the second subdivision band image is achieved by two dimension discrete wavelet packet transform in order to combine detail information of two images and to get legible results. The experimental results show that local standard deviation and local entropy of image obtained by twice fusion, compared with two original images, increase by 21.06% and 9.20% respectively, which proves the validity of fusion method above.