The invention relates to a welding method for an aluminum alloy small-diameter pipe nozzle of a storage tank, and belongs to the technical field of metal materials and technologies. The welding methodfor the aluminum alloy small-diameter pipe nozzle of the storage tank relates to welding structure form design and specific welding technological processes and is used for carrying out reliable connection between the 2219 aluminum alloy small-diameter pipe nozzle and a storage tank shell, an upper lock bottom annular boss of a special structure is designed in a welded junction of the small-diameter pipe nozzle, and the pipe nozzle of the structure is assembled to an opening of the storage tank shell to form an annular butt weld with the upper lock bottom structure. According to the method, the pipe nozzle and the storage tank shell are welded through high-energy beam welding to form a reliable welded joint. The method comprises the welding structure form design and a welding technologicalmethod.