The invention discloses a device for preparing semi-solid state pulp and conducting surface coating. The device comprises a servo motor I, a machine frame, an extrusion nozzle, a thermal insulation pipe, an adjustable-speed motor, a movable cross beam, a servo motor II, a water tank, a hydraulic cylinder, a resistance melting furnace, a hydraulic cylinder supporting base, a flow guide pipe, a workbench, a servo motor III, a pinion, a bearing I, a bearing II, a screw piston, a big gear wheel, an electromagnetic valve, a pressure valve, a sliding table, a sliding chute I, a sliding chute II and a sliding chute III. By the adoption of the device, the procedure of semi-solid state pulping and the procedure of surface coating are combined, high heat of the semi-solid state pulp is used for metallurgical bonding of a semi-solid state material and a base material, gradient materials of different structures can be obtained, the usability of the material surfaces is improved, the problem that the semi-solid state pulp is hard to store and transfer is solved, and processing efficiency is improved; and moreover, the application range of semi-solid state processing is widened, the device is easy and convenient to control, and the application range of alloy species and part structures is broad.