In order to solve the problem of limited internal space and difficult measurement of some workpiece, a point cloud rotating splicing method based on surface structured light was proposed. The reconstruction method of single field of surface structured light was introduced in this paper. The absolute phase value was obtained by combining four-step phase shift and complementary Gray code, and the camera and projector were calibrated by polynomial fitting method. The point cloud registration was studied based on the rotation plane of the wrist joint at the end of the manipulator. A calibration method based on the auxiliary camera was proposed, and the transformation relationship between the camera imaging coordinate system and the rotation plane coordinate system was given. The experimental results show that the method is suitable for measuring the inner wall of workpiece, and the average error of splicing is less than 0.05 mm, which meets the requirements of practical application.