The invention discloses a multi-material multi-scale 3D (3-dimensional) printing device provided with a single spray nozzle as well as a working method of the 3D printing device. The 3D printing device comprises a base, a work table, a bearing table, a substrate, a power supply, the spray nozzle and a bracket, wherein the base is mounted at the bottommost part, the bracket and the work table are mounted above the base, the spray nozzle is mounted on the bracket, the bearing table is fixed on the work table, and the substrate is fixed above the bearing table; an anode and a cathode of the power supply are connected with a nozzle body of the spray nozzle and the bearing table respectively; relative motion between the spray nozzle and the substrate in x, y and z directions is realized by the aid of relative motion between the work table and the bracket. The spray nozzle is provided with a plurality of feed openings connected with different trace feeding pumps, multiple materials are thoroughly mixed under the action of a stirrer after entering the spray nozzle, and multi-material printing is realized. The macroscopic geometrical shape as well as microstructures in an object and on the surface of the object is controlled reasonably, and multi-scale structural integrated manufacture is realized.