Aimed at the limitation of infrared obstacle detection and absolute positioning, the research was conducted to the cleaning robot intelligent tracing.The robot was used of ultrasonic sensor matched with a servo motor to construct an automatic obstacle avoidance system, to detect unknown indoor environment, which could also effectively overcome the shortcomings of infrared detection.On this basis, the multi path merging planning and control algorithm were put forward, which could make the robot to complete the autonomous region coverage walking.The experimental results show that, the control system has good response characteristics and good cleaning coverage rate, and can continuously work for a long period of time with good stability.