The invention discloses a preparation method of a lithium ion battery negative electrode material high-entropy oxide. The preparation method comprises the following steps: S1, carrying out oil removal, polishing and rust removal, distilled water washing, alcohol solution secondary washing and vacuum drying on a high-entropy alloy Cr<0.2>Fe<0.2>Mn<0.2>Ni<0.2>Co<0.2> solid; S2, conducting melting, carrying out gas atomization granulation, and conducting cooling and sieving; and S3, taking the high-entropy alloy powder, and conducting oxidation treatment under flowing oxygen, so as to obtain the required (Cr<0.2>Fe<0.2>Mn<0.2>Ni<0.2>Co<0.2>)<3>O<4> high-entropy oxide lithium ion electrode material. The lithium battery negative electrode material (Cr<0.2>Fe<0.2>Mn<0.2>Ni<0.2>Co<0.2>)<3>O<4> high-entropy oxide obtained through the method is a pure phase, the particle morphology is uniform, the particle size is 0.1-2 microns, namely, the material performance is more stable, a battery assembled by the lithium battery negative electrode material high-entropy oxide has very high specific capacity and very good cycle stability and has remarkable economic value, and the method is short in process, easy to operate, low in cost and suitable for industrial production. The method is high in controllability, good in repeatability, wide in applicability and suitable for industrial production.