Abstract: This paper introduces the architecture of an image-based visual servo robot system and the algorithm implemented to track a target with planar motion. This robot system has 5 degrees of freedom, which consists of a robot with 3 DOFs and a 2-DOF wrist attached to the end of the robot. And, a camera is fixed on the end of the wrist. With low inertia, the wrist rotates quickly to track the target, while the 3-DOF robot moves the camera to an appropriate position to take a close look at the target when needed. The system tracks the target successfully. Furthermore, this paper proposes some approaches to improve the system performance, and the experiments verify them.