The invention discloses a die for preventing deformation of a forge piece with a thin-wall hole in the punching process. The die comprises an insert die sleeve; the insert die sleeve is arranged in an upper die hole; the upper part of the insert die sleeve is fixed on an upper die body; a containing space for a movable insert is arranged in the insert die sleeve; the movable insert is arranged in the containing space; the upper part of the movable insert is connected to one end of a spring b in an abutting mode; the other end of the spring b is connected to a pre-tightening bolt in an abutting mode, wherein the pre-tightening bolt is connected to the upper part of the insert die sleeve in a screwed mode; an inclined surface is arranged on the side, close to a punch, of the insert die sleeve; one side of the inclined surface is connected to the side wall of the inner hole of the forge piece in an abutting mode, and the other side of the inclined surface and the side wall of the punch form a certain angle; and the shape and the size of the inner side of the inclined surface are consistent with the shape and the size of the inner hole in the upper part of the forge piece. The die has the advantages that the hole wall is restrained in the punching process, deformation in the punching process is prevented, and meanwhile, a pushing device for the forge piece is designed so that the phenomenon that the forge piece wraps the punch up and then cannot fall off due to hole shrinkage in the punching process can be prevented.