The invention discloses an extrusion forming mold for a cylinder with rib-equipped inner and outer special-shaped surfaces. The extrusion forming mold comprises an upper mold plate, a core shaft, a separated concave mold, a prestressed ring, a separated convex mold mechanism, a lower mold plate, an ejection mechanism and a mold release mechanism, wherein the upper end of the core shaft is fixedly arranged below the upper mold plate, and the lower end of the core shaft is provided with a cone-shaped head; the prestressed ring is arranged above a lower backing plate, and a straight-wall cavity is formed in the middle of the prestressed ring; an ejection rod mechanism comprises an ejection rod and an ejection block, the ejection rod is movably arranged in an ejection rod through hole of the lower mold plate, and the ejection block is arranged at the bottom of the straight-wall cavity; the separated concave mold is integrally and movably arranged in the straight-wall cavity and is longitudinally divided into more than two petals, a concave mold cavity is formed in the middle of the separated concave mold, and a inverted-cone-shaped mold-separating cavity is formed in the outer periphery of the top of the separated concave mold; the separated convex mold mechanism is integrally arranged in the concave mold cavity and comprises a separated convex mold and a convex mold fixing plate, an inverted cone-shaped cavity is formed in the middle of the separated convex mold, a cone-shaped head is formed at the outer periphery of the top of the separated convex mold, the separated convex mold is divided into more than two petals, and each convex mold can slide on the convex mold fixing plate along the radial direction; the mold release mechanism comprises a stroke extending block and a stroke returning ring, a cone-shaped ring cavity is formed in the middle of the stroke returning ring, and the stroke extending block is a wedge-shaped block.