That center wing box is jointed with fuselage bears and transfers plane load. The center wing box is also both fuel box and the fuselage，pressure cabin, and it supports the mid fuselage cabin floor, so the design of the center wing box is significant for the plane project. There appears different thought and plans for the center wing box of the commercial plane with the material science and the manufacture technique improving. This paper presents the application of composite material in the design of aircraft by comparing between the Project 1plane and the Project 2 plane.