With the continuous development of medical technology, it is very important for patients with upper limb injury caused by various reasons to carry out postoperative functional recovery treatment. In order to facilitate the clinical rehabilitation treatment after operation, the mechanical arm assisted with limb joint movement is used to help patients with rehabilitation training. However, due to the complexity of human limb movement, the axis of using the robot is not coincident with the axis of robot motion, and a certain position deviation is easy to restrict or even damage the elbow wrist joint movement of patients. In this article, based on the application of artificial intelligence technology, the motion pair of elbow wrist joint is equivalent to data, and the human body mechanism is equivalent to a multi-rigid body open chain mechanism. In the biological fusion elbow wrist rehabilitation manipulator composed of human body mechanism and mechanical structure, the length of human forearm is identified through the position analysis of elastic moving pair, and the elbow joint flexion and extension is realized by intelligent angle correction. In addition, the accuracy of motion control of rehabilitation robot is improved.