In order to improve the fitting accuracy of the stiffened skin profile, an adaptive fitting method based on the self-adaptive mould was proposed. The rubber was treated as the fitting surface. It was vulcanized and its surface was formed with that of the cured composite skin. Then, the rubber was attached to the steel mould to form an adaptive mould. The results showed that the cooperated clearance and interference were eliminated by the adaptive fitting of the unvulcanized rubber. There were no negative effects on the mechanical properties of composites, and the mechanical properties of the rubber could satisfy the requirement of adaptive fitting. What’s more, the effect of the method on the properties of composites was evaluated.