Existing infrared images have some problems such as low resolution and weak edge. To solve these problems,an infrared dim target extraction algorithm based on region characteristic segmentation is proposed. The target signals are extracted through infrared background and target contour according to the theory of gray morphology. Firstly,the object area and the background area in the image are separated according to the similarity of the gray and shape in the infrared images. Then,the target contour in the target area is extracted by using the edge detection algorithm. The results show that this algorithm can effectively extract the targets in the infrared image. It has the advantages of high precision and the strong ability of anti-interference.