The invention provides a preparation method of a positive electrode plate and polymer electrolyte membrane combined piece. The preparation method comprises the following steps: (1) carrying out ball-milling treatment on a positive active material and a ceramic-based solid electrolyte; (2) under heating, dissolving a polymer binder in an organic solvent, adding lithium salt, and performing stirringto completely dissolve the lithium salt; (3) taking the solution obtained at the step (2), adding a ceramic-based solid electrolyte, performing stirring, pouring the mixture into a mold, and evaporating the solvent to dryness to prepare a polymer electrolyte membrane; (4) taking the solution prepared at the step (2), adding the positive active material and the conductive additive at the step (1),performing stirring, coating an aluminum foil with the solution, and performing drying to obtain a positive electrode plate; (5) tabletting the positive electrode plate, combining positive electrodeplate with the polymer electrolyte membrane at the step (3), performing tabletting, and carrying out melting treatment to obtain the combined piece. According to the method, the compatibility of the positive electrode plate and the electrolyte membrane can be improved, the solid-solid interface contact of the solid-state battery is increased, and the impedance is reduced; the coulombic efficiencyof the battery is effectively improved, and the advantages of the electrode material are fully exerted.