Abstract: An ACO (Ant Colony Optimization) algorithm for TSP (Traveling Salesman Problem) with knowledge guiding pheromone control strategy is put forward.On the one hand,aiming at accelerating the convergence,the pheromone is initialized by the MST (Minimal Spanning Tree) information.On the other hand,the pheromone updating is guided by swarm knowledge,which is the intersection information of paths constructed by all ants.It can strengthen the collaboration of ants.The experimental results indicate that the proposed algorithm outperforms other ACO algorithms.