Provided is a lightweight aluminum alloy carriage, which relates to the field of lightweight logistics equipment manufacturing application. The lightweight aluminum alloy carriage comprises a bottom plate assembly, and the bottom plate assembly comprises a front end part and a rear end part which are arranged front and back on an axis; the front end part comprises a transversely arranged aluminum alloy profile bottom plate, and the extrusion direction of the transversely arranged aluminum alloy profile bottom plate is perpendicular to the axis of the bottom plate assembly; and the rear end part comprises aluminum alloy square tube cross beams and a longitudinally arranged aluminum alloy profile bottom plate, and the aluminum alloy square tube cross beams are perpendicular to the axis of the bottom plate assembly.