Si-O-C material was prepared by a polymer-derived method using copolymer of phenyl-substituted polysiloxane and divinylbenzene as raw materials. The porous Si/Si-O-C anode material was prepared with the chemical reduction of Si-O-C material by magnesium at high temperature under argon atmosphere. The composition, structure, morphology, and formation process of porous Si/Si-O-C anode material were investigated by X-ray diffraction, energy spectrum analysis, elemental analysis and field emission scanning electron microscope. The electrochemical properties of the material were characterized by using the electrochemical test instrument. The research results show that the magnesium will react with oxygen of Si-O-C material and turn into MgO and Mg₂SiO₄ during the reduction process. When washed with HCl, MgO and Mg₂SiO₄ react with HCl and turn into MgCl₂, which can dissolve in the solution. Then, the porous Si/Si-O-C anode materials are formed. The silicon distribute in the porous Si-O-C material, which can improve the cycle performance of silicon. It can confirms that the material prepared by using magnesium reduction method is a potential material for the lithium-ion battery.