The utility model relates to a butt welding slope angle adjustable device for bearing a metal plate body. The technical scheme is as follows: the device comprises a welding platform for bearing a metal plate body and an air support hydraulic rod capable of adjusting the angle of the butt welding platform, the two welding platforms can bear metal plate bodies with different thicknesses, lengths andwidths by adjusting the telescopic bearings; the two welding platforms are connected through a rotating shaft hinge capable of flexibly rotating, the adjustable welding platform is connected with thewelding platform box body through an air support hydraulic rod, the air support hydraulic rod is controlled by an electric button, and the butt welding slope angle of the metal plate body is adjustedthrough the electric button according to the specific requirements of the welding process. The device has the advantages of reducing the consumption of manpower and material resources and improving the butt welding precision and the welding efficiency of the metal plate body.