The present invention provides a lithium ion battery and a negative electrode material thereof. The negative electrode material includes a mixture of a graphite and an amorphous carbon, wherein the graphite is subjected to a surface treatment, and the surface treatment manner is a combination of mechanical fusion modification and spray drying coating, and wherein the graphite has a graphitization degree of 90-96%, an average particle diameter D50 of 13-25 μm and a specific surface area BET of 0.8-2.5 m2/g, and the amorphous carbon has a graphitization degree of 65-80%, an average particle diameter D50 of 2-15 μm and a specific surface area BET of 1.0-3.0 m2/g.