The paper aims to solve the problem of removing the carbon deposition from the inner surface of a large-sized aero-engine turbo-shaft. SEM was used to analyze the micro topography and the components of the carbon deposition to lay a foundation for determining the carbon removal method and process. Considering the special material and cleaning requirements of the turbo-shaft, magnetic grinding technology was proposed to clear carbon deposition. By the means of Solidworks and Workbench, the magnetic induction intensity and the forces on the grinding granules in the grinding area were analyzed. And magnetic grinding equipment which is composed of a CNC and auxiliary poles along the radial direction of the turbo-shaft was set up. Three kinds of average granule diameter, 185, 250, 375 μm, were selected to conduct the comparative experiments under the condition of the rotational speed of the workpiece being 600, 800, 1000 r/min respectively. During experiment, when the granule diameter was 250 μm, the rotational speed of the workpiece was 800 r/min, the grinding time was 60 min, and the machining gap between the external poles and the workpiece surface was 5 mm, the carbon deposition on the inner surface of the turbo-shaft was removed completely with a large removal amount and the surface roughness decreased substantially to Ra 1.47 μm. CNC magnetic grinding equipment can effectively remove the carbon deposition from the inner surface of a large-sized aero-engine turbo-shaft with high efficiency. The surface roughness of the inner surface of the turbo-shaft can reach Ra 1.47 μm which meets the working requirements of the workpiece.