Disclosed is a composite silicon negative electrode material. The composite silicon negative electrode material comprises a nano silicon (1), a nano composite layer (5) coated on the surface of the nano silicon, and a conductive carbon layer (4) uniformly coated outside the nano composite layer (5). The nano composite layer (5) is a silicon oxide (2) and a metal alloy (3). In the composite silicon negative electrode material with a three-layer structure, the nano composite layer (5), composed of the silicon oxide (2) and the metal alloy (3) coated on the surface of the silicon oxide (2), effectively reduces the volume expansion of the nano silicon (1), maintains the characteristic of high conductivity of the silicon material, improves the mobility of lithium ions, prevents direct contact between a silicon negative electrode and an electrolyte, and can form a hard SEI film on the surface of the composite silicon negative electrode material, thereby allowing the cycle performance of the material to be greatly enhanced. The composite silicon negative electrode material has the characteristics of a high capacity, long cycle life and high conductivity. A preparation process for the silicon negative electrode material is simple, easily controllable, and suitable for industrial production.