Friction stir welding manufacturing method for large-size high-thickness aluminum alloy panel

The invention discloses a friction stir welding manufacturing method of a large-size high-thickness aluminum alloy panel. The panel comprises a bottom plate and a cover plate. The method comprises thefollowing steps: 1, welding of the bottom plate: pre-welding assembly, front positioned welding, front preheating welding, front formal welding, front reinforced welding, back positioned welding, back preheating welding, back formal welding and back reinforced welding; 2, runner treatment of the bottom plate and the cover plate; 3, welding of the cover plate and the bottom plate: assembling, positioned welding of the cover plate and formal welding of the cover plate; and 4, post-welding heat treatment and machining of the panel, wherein the front preheating welding and the back preheating welding adopt friction stir welding preheating, heat is generated through friction of a stirring head shaft shoulder and a stirring needle, and the welding depth is 1/5 of that of front formal welding and that of back formal wel