Vertical clamps are representative large-capacity metallurgical lifting tool and wide spread employed to lift and to convey vertical cold or hot rolling steel coil of strip. To ensure absolute safety, the kinematics model of the vertical clamp was built, and its virtual prototype was established on Solid Edge, and the working process was simulated based on ADAMS environment. To explain the establishing mode of clamping force, the dynamic positive feedback working process of clamping was discussed. The correctness of simulation was validated by means of analytical investigation. The safe working conditions of vertical clamp were obtained.