By taking a high performance fixed-point DSP DM642 as a kernel processor, and a S3C2410 as a assistant control processor,an IR dual-band real-time image fusion system worked at Mid-wave Infrared (MWIR) and Long-wave Infrared (LWIR) is designed by using the high speed operation of DM642 and its configurable video ports combined with the powerful control capability of the S3C2410. An image fusion algorithm based on Discrete Wavelet Transform (DWT) is applied to the IR dual-band image fusion. Then,the algorithm is optimized to run on a DSP+ARM embedded hardware platform based on the features of real-time embedded system. The experiments demonstrate that it is only 39.6 ms to be needed to complete the real-time fusion of two IR images with the resolution of 320 pixel×240 pixel, which meets the engineering requirements of 25 frame/s.It also demonstrates that obtained images can show the characteristics of MWIR and LWIR, respectively.