Rear longitudinal beam assembly, welding method and automobile

The invention relates to the technical field of automobiles, in particular to a rear longitudinal beam assembly, a welding method and an automobile. The rear longitudinal beam assembly comprises a longitudinal beam upper reinforcing plate in a frame shape; an inner supporting frame which is arranged in the longitudinal beam upper reinforcing plate, wherein the inner supporting frame and the inner wall face of the longitudinal beam upper reinforcing plate are welded to form an inner reinforcing plate assembly; a rear longitudinal beam which is omega-shaped, wherein an internal reinforcing plate assembly is inserted on the rear longitudinal beam, and the rear longitudinal beam is welded with the internal reinforcing plate assembly; a longitudinal beam lower reinforcing plate which is omega-shaped, and is arranged on the longitudinal beam lower reinforcing plate in an inserted mode, wherein the longitudinal beam lower reinforcing plate and the rear longitudinal beam are welded to form the rear longitudinal beam