Abstract: It is hard to detect the infrared armor target because the background is so complex and the SNR of image is low. Consequently, a new background suppression method is put forward which bases on the wavelet and improved fractal theory. Filtering the low frequency background in image by using wavelet transformation, image with the target and edge clutter can be obtained. Because fractal dimension of target is much more sensitive than that of the edge clutter, so the edge clutter in background can be inhibited by calculating the rate of irregular factor of the image in different scale, so as to achieve a good background suppression effect. Experiment results show that this algorithm can significantly improve image signal-to-noise ratio (GSNR is about 2), and has good inhibition effect on undulate background.