A cutting robot for underground drainage pipe is designed to automatically reopen the lateral connection between main pipe and branch pipe after CIPP (Cured-in-Place-Pipe) installation.The robot can recognize the target cutting area by vision, and localize it by visual control and distance measurement. When the robot moves to the desired location and its arm rotates and stretches to the target cutting area, a drill---the end-effector of the robotic arm---will remove the excessive material.