The local contrast method is difficult to improve the significance of the target and suppress the background in infrared target detection, thus an enhanced local contrast method based on ring special preprocessing is proposed to detect targets. The high-frequency noise is removed by fast median filtering, the background is suppressed by improved morphological gradient, the significance of the target is improved by enhanced local contrast, and finally the real target to be detected is obtained by self-adaptive threshold. The results show that compared with the classical detection methods of human visual system, the proposed method has advantages in detecting infrared weak and small targets, and the effect is more significant in high brightness background.