Aiming at the current situation of dim target detection in infrared image, a dim and small target detection method based on the most appropriate contrast saliency analysis was proposed. In sliding serial port, the non-linear processing technology was used to process the image, which avoided the saliency produced by traditional saliency analysis algorithm when processing the image at the scene edge. The problem of value interference does not affect the ability of target extraction in the target area. A large number of hardware-in-the-loop simulation experiments were carried out. The results show that although the proposed method can not improve significantly in the background suppression factor, the performance of target detection in the two indicators of mean signal-to-noise ratio and signal-to-noise ratio gain of the proposed method are significantly enhanced. And among the three methods of image processing, the effect is the best.