Provided is a method for fabricating a modified-silicon-based negative-electrode material by vapor deposition; first, nano-silicon is mixed with a transition-metal compound aqueous solution, and the mixture is heated until moisture evaporates; next, a reducing agent is used to reduce the nano-silicon carrying the transition-metal compound, then an amorphous carbon source is used to deposit amorphous carbon onto the nano-silicon carrying the transition metal; lastly, an acidic medium solution is used to remove the transition metal on the nano-silicon having the amorphous carbon deposited thereon. A transition metal is used as a catalyst, such that the amorphous carbon and the nano-silicon are chemically bonded together; the amorphous carbon is deposited onto the nano-silicon to obtain a composite negative-electrode material of nano-silicon and amorphous carbon; the amorphous carbon has a porous structure that mitigates the silicon-powder volume expansion resulting from electrical charging and discharging; at t
