Abstract: A algorithm of visual range prediction based on PSO is proposed in this paper. Firstly, the existing method of visual range prediction is analyzed in detail, and the getting method of some complex parameter is obtained based on assuring precision.Then,the PSO is imported by confirmming the temperature difference of target and background,and the spacial frequency of target, which is hard to calculated. Finally, the farmost detecting distance of target is obtained in corresponding identification probability.Experimental results show that the method can reduce the detecting distance range of target,improve the algorithm precision.Meanwhile,the method also can used to any target.