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.