The invention discloses a mechanical automatic grabbing device. The mechanical automatic grabbing device comprises two supporting columns, a supporting plate and a grabbing device body. The two supporting columns are connected by the supporting plate, and a controller, a display screen and a buzzer are arranged on one of the supporting columns; a transverse groove is formed in the lower surface ofthe supporting plate, a lead screw is transversely arranged in the groove, a moving block capable of moving along the lead screw is connected to the lead screw, and the grabbing device body is fixedly arranged at the lower end of the moving block; the grabbing device body comprises a hydraulic cylinder, a telescopic rod and a mechanical gripper; the upper end of the hydraulic cylinder is fixedlyconnected with the lower end of the moving block, the hydraulic cylinder is electrically connected with the controller, and the lower end of the hydraulic cylinder is fixedly connected with the telescopic rod; and a connector is arranged at the lower end of the telescopic rod, the lower end of the connector is movably connected with the mechanical gripper through a rotating shaft, and an infraredsensor and a gravity sensor which are electrically connected with the controller are arranged on the telescopic rod. Compared with the prior art, the mechanical automatic grabbing device is capable ofimproving grabbing precision, high in working efficiency, simple in structure and convenient to use.