Composite as excellent aviation material is widely used due to its high intensity, stiffness and designable performance. In order to satisfy manufacture process and maintain requirement ,the center wing rear spar needs to open hole. The strengthening structure on composite is more complex than that on metal structure because of composite material anisotropic characteristics. This paper describes large opening design on composite and verifies with experiments. The research can provide technical support for the large opening design on the rear spar of composite center wing.