The invention relates to a Li-ion secondary battery cathode material preparation method with a nuclear shell structure; the preparation method is characterized in that: SiO, asphalt and graphite are weighted and are added in solvent for carrying out stirring; drying is carried out; the solvent is extracted out to obtain precursors which are uniformly distributed; the precursors are arranged in a high-temperature furnace, high-temperature sintering is carried out at inert atmosphere, the temperature is reduced to room temperature, so as to obtain the Li-ion secondary battery cathode material preparation method with the nuclear shell structure; meanwhile, the SiO, the asphalt and the graphite are chosen as initial raw material, so as to prepare the Si-SiO2-C electrode material with the nuclear shell structure, when the volume of the buffering Si material is expanded, the electricity-conducting capacity of the electrode material is ensured and the electro-chemical Li-embedded reaction property of the electrode material is improved; the asphalt is used as a carbon source, while reducing the product cost, the material is coated; a regular carbon layer structure is set up in the material body and on the surface, so as to improve the electricity-conducting performance of the material; the method has simple process and is suitable for large-scale industrial production.