Making large automatic device for polishing freeform surface of large mold has many disadvantages. We propose a new thinking of polishing large freeform surface with small mobile robot, and develop a novel small mobile polishing robot which has good maneuverability for moving on and polishing curved surface continuously. By analyzing its kinematics model, algorithm for tracking polishing path is designed, in which discrete points along planed polishing path on surface are taken as robot’s navigation points. And virtual robot view methods are designed in the tracking algorithm to avoid the oscillate phenomena. Both the simulation and field experiments prove that this type robot can satisfy the requirement of polishing process.