The invention discloses a composite anode material for lithium ion batteries and a preparation method thereof. The composite anode material for lithium ion batteries comprises in-situ synthesized vanadium dioxide, nanometer silicon surface-coated with vanadium dioxide and asphalt modified spherical graphite with surface uniformly dispersed with nano-scaled silicon. The preparation process comprises the following steps: uniformly dispersing activated nano-scaled silicon, asphalt modified spherical graphite and a vanadium source in a medium solution and drying to obtain a precursor; conducting two-stage sintering on the precursor in the inert atmosphere and then cooling and grinding so as to obtain the composite anode material for lithium ion batteries. By the preparation method, cycling stability and rate capability of the prepared composite anode material for lithium ion batteries can be effectively enhanced.