Abstract: The paper presents an automatic binding manipulator of steel bars. It described the binding principle, model analyzing and theoretical computing. And it designed the device using Pro/Engineering software. Using Φ6.5 steel wire, the manipulator can bundle up steel bars automatically with a programmable controller(PLC), driven by hydraulic motor. The strapping knot with 720°can fit all kinds of binding criterions of steel bars. It has been applied to finishing craftwork successfully.