A method for manufacturing a self-clinching rivet through extrusion forming, the method comprising: upset-extruding a first end of a wire blank to shape the first end into a material pushing portion and an annular shank portion billet, wherein the shank portion billet extends axially along the wire blank, and wherein the shank portion billet is located at a lower side of the material pushing portion, and a lower side surface of the shank portion billet comprises an upwardly concave surface forming a tapered portion wherein said shank portion billet has a cross-sectional area gradually decreasing from top to bottom; or wherein the shank portion billet is located at an upper side of the material pushing portion, and an upper side surface of the shank portion billet comprises a downwardly concave surface forming a tapered portion wherein said shank portion billet has a cross-sectional area gradually increasing from top to bottom; upset-extruding the shank portion billet, such that the tapered portion flows in a direction away from the wire blank, thereby forming a shank portion extending in a radial direction of the wire blank and a groove portion between the shank portion and the material pushing portion, wherein the shank portion has a cross-sectional area which gradually increases from its first end adjacent to the material pushing portion to its second end away from the material pushing portion; wherein the material pushing portion is configured to press against a panel material to make it flow into said groove portion when in use; upset-extruding a second end of the wire blank to shape the second end into a slot shaft portion, thereby forming a slot portion between the slot shaft portion and the material pushing portion or the shank portion, wherein the second end of the wire blank is disposed opposite to the first end of the wire blank. upset-extruding a first end of a wire blank to shape the first end into a material pushing portion and an annular shank portion billet, wherein the shank portion billet extends axially along the wire blank, and wherein the shank portion billet is located at a lower side of the material pushing portion, and a lower side surface of the shank portion billet comprises an upwardly concave surface forming a tapered portion wherein said shank portion billet has a cross-sectional area gradually decreasing from top to bottom; or wherein the shank portion billet is located at an upper side of the material pushing portion, and an upper side surface of the shank portion billet comprises a downwardly concave surface forming a tapered portion wherein said shank portion billet has a cross-sectional area gradually increasing from top to bottom; wherein the shank portion billet is located at a lower side of the material pushing portion, and a lower side surface of the shank portion billet comprises an upwardly concave surface forming a tapered portion wherein said shank portion billet has a cross-sectional area gradually decreasing from top to bottom; or wherein the shank portion billet is located at an upper side of the material pushing portion, and an upper side surface of the shank portion billet comprises a downwardly concave surface forming a tapered portion wherein said shank portion billet has a cross-sectional area gradually increasing from top to bottom; upset-extruding the shank portion billet, such that the tapered portion flows in a direction away from the wire blank, thereby forming a shank portion extending in a radial direction of the wire blank and a groove portion between the shank portion and the material pushing portion, wherein the shank portion has a cross-sectional area which gradually increases from its first end adjacent to the material pushing portion to its second end away from the material pushing portion; wherein the material pushing portion is configured to press against a panel material to make it flow into said groove portion when in use; upset-extruding a second end of the wire blank to shape the second end into a slot shaft portion, thereby forming a slot portion between the slot shaft portion and the material pushing portion or the shank portion, wherein the second end of the wire blank is disposed opposite to the first end of the wire blank.