Composite beam of external hanging chunks slide rail lower portion

A composite beam of an external hanging chunks slide rail lower portion comprises a composite beam and a plurality of reinforced rib plates mounted at two sides of the composite beam, wherein a cross section of the composite beam is a frustum shape; an upper flange plate of the composite beam is respectively wider 250mm than a lower flange plate along a center; and the plurality of reinforced rib plates are welded on the composite beam by the way of using one meter interval. According to the utility model, after the deviation of the external hanging chunks and an original old platform occurs, the external hanging chunks and the slide rail of the original platform are smoothly butted, and the problem that the misalignment of the rail in the butting of the new and old platforms is overcome.