The invention discloses a high-aluminum thermal-spraying solid-core wire and a preparation method and application thereof. The wire is composed of 18-22% of Al, 0.1-0.5% of Mg, 0.1-0.5% of RE, less than 0.05% of impurities and the balance Zn, wherein RE is misch metal. The preparation method comprises the steps of (1) preparing Zn-Al-RE10 intermediate alloy, pressing an aluminum rare earth alloy block into liquid zinc after zinc is melted, and performing even stirring and casting after melting; (2) performing alloy casting, heating and melting pure zinc and pure aluminum, preserving heat and adding the Zn-Al-RE10 intermediate alloy; adding a magnesium block after the Zn-Al-RE10 intermediate alloy is melted, processing melted liquid through a refining agent and a leavening agent after the magnesium block is melted, and performing casting after the processing; (3) extruding alloy, performing annealing treatment on cast ingots firstly, and then performing extrusion treatment under the effect of lubricants after preheating; (4) drawing the wire, carrying out hot drawing on the alloy firstly and then carrying out cold drawing on the alloy, and carrying out annealing treatment on the alloy in the hot drawing process and the cold drawing process; and (5) cleaning the wire and winding the wire on a reel.