The invention relates to a multifunctional portable power assisting device used for solo express. The multifunctional portable power assisting device comprises an express box base and a foldable planet gear goods carrying trolley. The express box base comprises an express box fixing box body, a goods carrying trolley clamping groove shell and an express trolley rear seat fixing frame, all of which are sequentially arranged from top to bottom. The foldable planet gear goods carrying trolley is folded and then horizontally clamped in the goods carrying trolley clamping groove shell. The express trolley rear seat fixing frame is fixed to an express trolley rear seat. Compared with the prior art, the multifunctional portable power assisting device has the beneficial effects that the labor intensity of carrying goods upstairs is relieved, the work efficiency is greatly improved, the space use rate is increased, and operation is convenient and quick.