Molding method of section

The invention discloses a molding method of a section. The section comprises an outer wall and an inner rib in the outer wall. The molding method is characterized by comprising the following steps that (1) the inner rib is manufactured through an extruding die, and the inner rib is cooled and shaped for use; and (2) after the inner rib is inserted in a cavity of a co-extrusion die head through the feeding opening end, outer wall section base materials are added into the co-extrusion die head, the inner rib and a fused outer wall parison are extruded together, and cooling and shaping are carried out. According to the molding method, one-step extrusion of the section is changed into two-step extrusion, the problem that the inner rib of the section is hard to cool is solved, and the molding method has the advantages of being reasonable in design, convenient and feasible, low in cost, high in production efficiency, high in yield and the like.