Abstract: A PSO-based live wire interactive image segmentation algorithm was proposed to solve the problems that the objective contour is easily influenced by imaging artifacts and imaged at low computation speed. With a new cost function formulated, the gradient amplitude change function between adjacent nodes was introduced into the new cost function to reduce the interference due to imaging artifacts and improve the segmentation accuracy. To improve the implementing efficiency of the algorithm proposed, PSO was applied to finding out the shortest path between any two points in image so as to locate the objective edge, and the relevant results were compared with the typical Live Wire image segmentation algorithm based on the search by the Dijkstra algorithm. It was found that the proposed algorithm is more accurate and efficient.