In order to monitor the six-DOF deformation via monocular vision, a circle-pair tracking algorithm based on direction-prediction, a contour extraction algorithm and an occlusion identification method based on watershed, were studied, and a monitoring system based on embedded platform was designed and developed.The system consists of a target module, a visual collecting module, a CPU module and the result display interfaces. There are 5 pairs of circular white marks of the same size on the target module, which fix the target on the outside surface of an object to be monitored. Through tracking the relative positions of the 5 pairs of marks, the displacements and rotation angles of the object to be monitored in Cartesian rectangular coordinate can be calculated.