To enhance the information from different sensors and improve the analytic and extracting ability of images, an algorithm of image fusion based on the wavelet packet transform is proposed after studying the wavelet packet analysis method. Although the analyzing method based on the wavelet packet is more accurate than that based on the multi-resolution wavelet, with the former method, computing complexity is exponentially increased with the growth of image size. After analyzing the efficiency of image fusion algorithm based on the wavelet packet on the single computer, the inherent complexity and the parallelism of the above fusion algorithm, a parallel image fusion based on wavelet packet in the MPI (message passing interface) framework is proposed. In addition, the efficiency of parallel computing is studied under different conditions as different image size and different cluster size. The experimental result shows that the efficiency of parallel computing is obviously improved and this paves the way for the future design of highly efficient and real-time fusion algorithms.