The invention relates to a method for manufacturing a decoction dreg/fibroin composite flowerpot. The method comprises the following steps: firstly, crushing traditional Chinese medicine dregs so as to obtain decoction dreg granules, mixing with ethanol and methylbenzene in a volume ratio of 1:2 so as to obtain a mixed solution, further mixing in a mass ratio of 1:20 so as to obtain a material liquid, filtering the material liquid so as to obtain filter residues; performing dehydration treatment on the filter residues in a centrifugal dehydrator, drying in a drying tank, and exploding in a steam exploder so as to obtain a decoction dreg fiber; extruding and mixing the decoction dreg fiber, fibroin, a coupling agent, a hardening agent, an antioxidant, a moisture absorber and a toughening agent in a double-screw calender so as to obtain a decoction dreg/fibroin composite material; finally injecting the composite material into a mold cavity of a flowerpot mold from an extrusion blowing machine at a melting state, cooling, and molding, thereby obtaining the flowerpot according to the shape of the mold cavity. The flowerpot manufactured by using the method is high in strength, good in toughness and good in aging resistance.