The invention provides a die fixing device for a punching machine tool, and relates to the field of punching machine tools. The device comprises an operating platform, wherein supporting legs are fixedly connected to the bottom part of the operating platform; a steel supporting plate is fixedly connected to the top part of the operating platform; a transverse supporting plate is fixedly connectedto the top part of the steel supporting plate; a hydraulic cylinder is fixedly connected to the bottom part of the transverse supporting plate; an upper die plate is fixedly connected to the output end of the hydraulic cylinder; a positioning pin is fixedly connected to the bottom part of the upper die plate; a chute is formed in the top part of the operating platform; a first sliding block is glidingly connected into the chute; and a fixing block is fixedly connected to the top part of the first sliding block. According to the device, a propping screw penetrates a fixing nut and a rectangularbock and is in contact with the fixing block at the left side of the rectangular bock, so that a lower die block can be conveniently fixedly mounted; the problem of releasing of the die is effectively prevented; and the damage of the die is effectively reduced.