Abstract: A new method based on macro-micro robot for weld seam tracking is presented.The positions of several teaching points on the weld seam are obtained via a simple teaching method,and the welding seam model is set up via fitting. Then the macro motion of the robot is planned according to the model.The coordinate of the weld seam is measured with a laser structured-light vision sensor,and the image error of the weld seam is employed to control the micro motion of the robot.With the combination of the planning macro motion and the adjusting micro motion,the welding seam tracking with high accuracy in large working range can be realized.A series of experiments are conducted with a macro-micro motion platform,and the experimental results demonstrate the validity of the proposed method.