The invention discloses a silicon-carbon composite material and a preparation method thereof, and a lithium ion battery. The method comprises the following steps of (1) coating porous carbon on porous silicon dioxide; (2) reducing the porous silicon dioxide to porous silicon by using a metal more active than silicon to obtain a porous carbon-porous silicon-metal oxide composite; and (3) etching the metal oxide in the carbon-porous silicon-metal oxide composite to obtain the silicon-carbon composite material. In the silicon-carbon composite material, the porous silicon is prepared by a metallothermic method; the porous silicon particles prepared by the metallothermic method are in micron size, so that agglomeration rarely occurs; and pore walls in the porous silicon particles and apertures are in nano size. Compared with imporous micron silicon powder, the silicon-carbon composite material shortens diffusion paths of lithium ions in silicon matrix, thereby facilitating large-current discharge; the holes in the porous silicon particles can accommodate volume expansion in a silicon-embedding process; and charge-discharge cycle life of the material is prolonged.