The invention relates to a modular optical moving mirror centering structure and a processing method, and particularly to an optical moving mirror centering structure which can be modularly processed, assembled and detected and the processing method thereof. The modular optical moving mirror centering structure comprises a moving mirror and a mirror frame. The mirror frame comprises an inner mirror frame and an outer mirror frame. The mirror frame is fixed in the inner mirror frame. The inner mirror frame is mounted in the outer mirror frame. A linear rolling bearing which is composed of steel balls and a steel ball holding frame is arranged between the outer circumferential surface of the inner mirror frame and the inner circumferential surface of the outer mirror frame so that the inner mirror frame can slide in the outer mirror frame in an axial direction. The outer mirror frame is provided with optical centering processing outer circumferential surface. The optical moving mirror centering structure provided by the invention can perform modular processing, assembling and detection and furthermore has functions of settling technical problems of single mounting and detection of the moving mirror and a driving guiding assembly, reducing machining precision of mechanical components, ensuring realization of an optical design requirement, realizing easier control for product quality, and facilitating serialization and standardization in production.