An opening biconical nut expansion bolt and a manufacturing device thereof aim at realizing simple and convenient operation and wide application range; the opening biconical nut expansion bolt comprises a bolt rod, a gasket, an expansion tube and a biconical nut, the biconical nut is a supporting and tightening element, the middle section is a cylinder, and two heads are cones; the outer surface of the middle cylinder is provided with axial straight knurling; the manufacturing device comprises a feeding part, a heating part, a rolling part, a molding part and a machine body; the feeding part comprises a material disk, a material disk shaft, a bracket and flat steel coiled material; the heating part comprises a guide wheel, a guide wheel bracket, an electromagnetic inductive furnace body and an electromagnetic inductive furnace coil; the rolling part comprises two pairs of rollers, an anvil, a cutter and a stop iron; the molding part comprises a central pressing roller, a pushing double-pipe and an embracing hoop device; the embracing hoop device comprises a left embracing jaw, a right embracing jaw, a fixing bracket, a traction slider and two connecting rods; and an upper plane ofthe anvil and a lower plane of the flat steel are parallel and level, and the distance between the planes and the stop iron is equal to the circumference of the external diameter of the biconical nut.