The invention relates to a self-deboosting tightening manipulator for a C type groove precise screw tightening robot. A connecting cylinder is used for fixing an electromagnet; one end of a central shaft penetrates through a central hole to be corresponding to an iron core; the interior angle of an L-shaped connecting rod is towards the central shaft; a guiding block is provided with three first sliding chutes, and the opening of each of the first sliding chutes is T-shaped; the first sliding chutes are arranged in the radial direction of the guiding block and communicate with each other; centrifugal blocks are positioned in the first sliding chutes; the upper end of each of the centrifugal blocks is T-shaped; the upper ends of the three centrifugal blocks fit the center to form a triangular first concave pit; the lower surface of each of the three centrifugal blocks is fan-shaped; the lower surfaces of the three centrifugal blocks fit to form a complete circle; an arc-shaped second concave pit is arranged on the outer surface of the lower end of each of the three centrifugal blocks; first springs are arranged in the second concave pits; and a clamping claw is arranged in a secondsliding chute. The self-deboosting tightening manipulator has the characteristics of transmitting larger tightening torque and effectively preventing the slippage phenomenon.