The invention discloses a preparation method of an all-solid-state lithium battery with high specific energy. The preparation method comprises the following steps: forming pores in coating processes of a positive pole piece and a negative pole piece by using a pore forming agent; rolling the prepared pole pieces, and then, coating a thin-layer polymer electrolyte solution on the surface of one side of each pole piece; and finally, winding or laminating the positive pole piece and the negative pole piece with electrolyte layers at one sides so as to be assembled into an all-solid-state lithiumion battery. Compared with the prior art, the method disclosed by the invention has the advantages that the polymer electrolyte solutions can permeate into the pole pieces through the pores obtained by the pore forming agent, and the interfacial contact area between each pole piece and the polymer electrolyte is larger, so that the ionic conductivity of an electrode material is increased; and theall-solid-state lithium battery prepared by the method has the advantages of low interfacial resistance, high energy density, high stability and safety and the like.