The invention discloses a manipulator wrist positioning system and a positioning method of the manipulator wrist positioning system, wherein the positioning system comprises an outer shell, a positioning structure, a servo motor, a first rotating shaft, a disc, an extension rod, a cylinder, a sheave, a second rotating shaft, a connecting plate, an inner shell, fixed plates, a manipulator steeringplatform, manipulator arm levers, rotating chucks and vacuum suction cups. The rotating chucks are driven by an air cylinder, so the rotating chucks can rotate in the vertical direction, and the practicability of a manipulator is improved; by installing the vacuum suction cups, the gripping effect of the manipulator can be improved, and uniform stress and stable clamping are achieved; through rotating fit of the disc, the sheave and the servo motor, rotating and positioning work of the manipulator in four directions can be realized, an external air cylinder is avoided from being used for positioning the manipulator, the cost is reduced, the positioning effect is excellent, and the stability is high. In conclusion, the movement speed of the manipulator can be controlled, the positioning effect is excellent, and the precision is accurate.