A novel infrared image segmentation algorithm for realizing infrared ship segmentation in the lower contrast and complicated background was presented.2-D Otsu method not only considers the distribution of the gray information,but also takes advantage of the spatial neighbor information by using the 2-D histogram of the image,so it often gets better anti-noise performance.However,its time-consuming computation is often an obstacle in application.Particle swarm optimization(PSO) algorithm can realize parallel,random and self-adapt colony search,hence an algorithm for PSO-based local recursive 2-D Otsu segmentation was proposed here.This algorithm can also be used in other infrared image segmentations with complicated backgrounds.