The invention discloses a mechanical arm structure for restoration of cultural relics, which includes an adjustment mechanism and a restoration arm, the restoration arm is installed on the adjustment mechanism, and the adjustment mechanism is used to adjust the position of the restoration arm in space; the restoration arm includes an inner connection plate, an upper Inner shaft, lower inner shaft, repair knife, upper outer cylinder, lower outer cylinder and multiple guide ropes; the first bearing and the second bearing are installed on the inner connection plate, the repair knife is detachably installed on the lower part of the lower inner shaft, and the upper outer cylinder The upper inner shaft is rotatably installed, the lower outer cylinder is rotatably installed on the lower inner shaft, the second upper connecting frame is installed on the lower part of the upper outer cylinder, the third bearing is installed on the outer side of the second upper connecting frame, and the lower outer cylinder is installed on the outer side. There is a fourth bearing, and the outer ring of the third bearing is provided with a guide hole for the guide rope to pass through, and the guide rope passes through the guide hole and is connected with the outer ring of the fourth bearing. The invention is easy to manufacture and use, the repair knife can flexibly complete the position change, and effectively overcomes the problem of inconvenient operation by human hands in a narrow space.