The invention provides a lead wire automatic clamping device used for a rotor lead wire slitting machine. The device includes a fixing structure, a driving mechanism, a rotor lead wire clamping mechanism, push air cylinder, a push block, a punch and a clamping arm. The rotor lead wire clamping mechanism includes a rotor lead wire clamping mechanism fixing base, the upper end of the back surface of the rotor lead wire clamping mechanism fixing base is fixed on a slider in a wire rail, and the lower end of the back surface of the rotor lead wire clamping mechanism fixing base is fixed on a synchronous belt; the push block is fixed on a telescopic end of the push air cylinder, the tail portion of the punch is fixed with the push block in a screw joint mode, and the clamping arm is movably connected with the rotor lead wire clamping mechanism fixing base through a hinge pin and relatively fixed to the rotor lead wire clamping mechanism fixing base. The device has the advantages that 1, the same rotor lead wire clamping device can act on various clamping arms different in type, and the practicality of the device is improved; 2, in the rotor lead wire clamping process, the clamping arm can automatically pull back.