The invention provides a preparation method of an all-solid-state lithium battery composite electrode material. The preparation method comprises the following steps of (A) mixing an electrode active material, a sulfide electrolyte and a solvent, so as to obtain a precursor solution of the composite electrode material; (B) carrying out suction filtration on the precursor solution of the composite electrode material, and drying, so as to obtain precursor powder of the composite electrode; (C) sintering the precursor powder of the composite electrode under the protection atmosphere, so as to obtain the composite electrode material. The preparation method provided by the invention has the advantages that the distribution of the electrolyte at the surface of an active matter of an electrode is improved; when the obtained all-solid-state lithium battery composite electrode is applied to an all-solid-state lithium battery, the first-time efficiency, cyclic property and rate property of the all-solid-state lithium battery are improved.