The invention discloses a perforating structure on a reactor pressure vessel convex head. The perforating structure is divided into three sections including an upper spigot section through hole, a middle interference fit section through hole and a lower spigot section through hole, and each of the diameter of the lower end surface of the upper spigot section through hole and the diameter of the upper end surface of the lower spigot section through hole is larger than the diameter of the middle interference fit section through hole, so that the processing difficulty of perforation can be reduced, and the processing accuracy of the middle interference fit section through hole is improved.