Abstract: In order to reduce the influence of background on detection results of infrared small targets and reduce false alarm rate, infrared background suppression algorithm based on guidance filter and fuzzy algorithm was adopted. The infrared image was decomposed into low-pass band and band-pass band by using multi-scale and multi-direction decomposition mechanism of non sampled contour. The guided filter was used to process low-pass sub-band to smooth images, suppress noise and enhance background details. Band-pass sub-band was processed by fuzzy algorithm to seperate the target from the residual background. Background suppression image was obtained by changing subband images through non subsampled contour inversion. The results show that, the method can reduce mean square error to 5~10, and effectively suppress the background and highlight the target. This study provides the support for improving the detection accuracy of infrared small targets in complex background.