The present invention provides a lithium ion battery negative electrode preparation method. The preparation method comprises the steps: providing a first graphite material, a second graphite material and a third graphite material, wherein the average particle size D1 of the first graphite material is 2.2-2.4 microns, and the average particle size D2 of the second graphite material is equal to k1 * D1, k1 is in the range of 1.42 to 1.45, the average particle size D3 of the third graphite material is equal to k2 * D1, and k2 is in the range of 0.56 to 0.58; mixing a first graphite material, a second graphite material and a third graphite material according to a preset mass ratio, wherein the first graphite material: the second graphite material: the third graphite material is 1: (c1 * k1): (c2 * k2), and c1 is 0.56, and c2 is 0.82; adding a binder, a graphite material and a conductive agent into deionized water in sequence to obtain negative electrode slurry, coating a negative electrode current collector with the negative electrode slurry, performing drying, carrying out hot pressing to obtain a pole piece, putting the pole piece and a counter electrode lithium piece into an electrolyte, carrying out electrochemical lithium pre-embedding, taking the pole piece out of the electrolyte, and performing drying to obtain the negative electrode. The negative electrode obtained by the preparation method disclosed by the invention is high in energy density and long in cycle life.