A new method for image edge detection is proposed based on particle swarm optimization through analyzing traditional methods for edge detection.The experimental results show that the proposed method has high randomicity by using individual random velocity in the solution space to change the position of the individual,and that the detected image edge is much clearer and more robust by using the proposed method than by using traditional methods.And compared with other optimization methods,such as Genetic algorithm(GA),the proposed method is very convenient and has no complex process of GA with crossover operators and mutation operators.