Abstract: Aiming at the grinding rod with large length-diameter ratio used for machining a non-rotating cone cover, the machining simulation method is adopted to explore its maximum size without collision. Initial size of grinding rod is determined and 3D model is established. CATIA software is used to generate the machining track covering the inner surface of cover, and a special post-processor is developed to generate G code. The machining simulation is completed by VERICUT software. According to the simulation results, the structure of grinding rod is optimized, the diameter of collision place is reduced, and the diameter of non-collision place is increased. The length of grinding rod is 1 855 mm and the diameter of big end is 150 mm after optimization. The final simulation proves that the maximum size of grinding rod without collision is determined by simulation method.