The self-rotating three-dimensional (3D) visual scanning system is a prevalent technique for 3D reconstruction. However, the misalignment of the scanner’s rotation axis with the camera’s origin often necessitates specialized calibration tools to establish their relative positions. We propose a rotating axis calibration method for the rotation axis, which eliminates the need for specific tools. A rotating mechanism is used to rotate the 3D camera to different angles and carry out 3D reconstruction of the same object with curved surface characteristics, respectively. The resulting sequence of 3D point clouds is registered to derive the camera’s position transformation matrix corresponding to each rotation angle. Subsequently, we compute the positional relationship between the camera and the rotation axis by solving the equation. To prevent excessively large rotation angles that would cause the object beyond the camera’s field of view, the camera field extension method is proposed, which enhances equation redundancy and leads to improved calibration accuracy. Experiments prove the flexibility and accuracy of the proposed method.