Industrial computed tomography (ICT) is an advanced nondestructive testing technology. The selection of threshold is one the general methods in ICT image segmentation, but often the selection of the optimal value for threshold is a challenge for researchers. In this paper we proposed a fast and optimal method for selection of good enough threshold value based on the improved Particle Swarm Optimization algorithms. To achieve the good result and stability in the proposed method, natural selection theory of Darwin's are applied with PSO and Otsu method. Moreover, the proposed method has been applied in various experiments in comparison with famous methods based on several ICT Images. Experimental results demonstrated that the proposed method outperformed better in comparison of other.