The invention discloses an automatic clamp tong mechanism of a numerically-controlled punch press. The automatic clamp tong mechanism comprises a locking air cylinder, a connecting plate, a punch press table top and a positioning air cylinder; the top end of the bottom of the connecting plate is connected with two cam crank arms which are symmetrically arranged, a camshaft is arranged at the bottom of each cam crank arm, each camshaft is connected with a push rod, a locking plate is arranged under the push rods and slidably connected to the side wall of a dovetail-shaped slide rail, and the locking plate and the dovetail-shaped slide rail are both located over the punch press table top; the punch press table top and the positioning air cylinder are connected through two positioning pins, the positioning pins fix a clamp tong body in a clamping mode, and a position sensor is arranged at the edge of the punch press table top and electrically connected with the dovetail-shaped slide rail. According to the clamp tong mechanism, the clamping function of a double-cam push rod clamp tong is reliable, and a self-locking function is achieved; the phenomenon that the clamp tong is loosened due to the fact that an air source fluctuates, loses voltage and loses power cannot occur; meanwhile, real-time monitoring is performed through the position sensor, and then safety interlocking of electric appliances is achieved.