The invention provides a shaping die on the headsill side of an automobile side wall. The shaping die comprises a lower convex die, a side shaping knife and an upper pressure plate, wherein a convex die surface matched with the upper pressure plate is arranged on the lower convex die, and the upper end of a board forming the headsill side of the automobile side wall is clamped between the upper pressure plate and the convex die surface; a side shaping groove matched with the side shaping knife is formed in the lower part of the convex die surface of the lower convex die, the side shaping groove comprises an upper shaping surface matched with the top surface of the side shaping knife, a side shaping surface matched with the end surface of the side shaping knife and a lower shaping surface matched with the bottom surface of the side shaping knife, and a segment of convex die extension surface is further arranged below the side shaping groove. When the side shaping knife of the shaping die moves in the side shaping groove, the tail of the board forming the headsill side of the automobile side wall flows into a gap between the side shaping groove and the lower shaping surface along with the side shaping knife, the tail of the board is restricted due to the effects of extrusion and frictional force between the side shaping groove and the lower shaping surface, and thus a generated product is free of wrinkles, high in surface quality, attractive in appearance and high in product qualified rate.