A novel mobile robot obstacle avoidance method based on multi-sensor was proposed. According to distant and near obstacles’ information detected by three front-end sonar sensors and four PSD sensors respectively, after analyzing the information data, obstacles distance and azimuth information were obtained , further, making strategy in the direction of motion and movement speed respectively according to the obstacles azimuth information and obstacles distance information. So, robot could realize the autonomous patrol through the finite state transition. Finally, experiments based on AS-R mobile robot platform shows that the method is feasible and reliable.