The invention relates to a composite 
silicon negative 
electrode material. The composite 
silicon negative 
electrode material comprises nanometer 
silicon, a nanometer composite layer 
coating the surface of nanometer silicon and a conductive 
carbon layer uniformly 
coating the nanometer composite layer, wherein the nanometer composite layer is 
silicon oxide and 
metal alloy. According to the composite silicon negative 
electrode material with a three-layer structure, the nanometer composite layer composed of the 
silicon oxide and the 
metal alloy coating the surface of the 
silicon oxide effectively reduces 
volume expansion of the nanometer silicon, maintains the characteristic of 
high conductivity of the silicon material, improves 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 substantially enhanced. The composite silicon negative 
electrode material has the characteristics of high capacity (greater than 1500 mAh / g), long cycle life (with a capacity 
retention ratio of more than 90% after 300 cycles) and 
high conductivity. The preparation method for the composite silicon negative 
electrode material is simple, easily controllable, and applicable to industrial production.