According to the structural characteristics of air duct, in view of the characteristic of design and manufacturing integration in composite material, combined with the basic principle of structural mechanics of composite material, a feasible structural layout and optimization design scheme of composite material air duct for Air-Cushion Vessel (ACV) is proposed. Based on the multi-constraint objective optimization, the overall layout design and optimization of structural configurations and sizes in air duct and internal strengthening structure are performed, and the equivalent analysis of limit overload of duct structure is made with the finite element analysis method. The calculation results show that the composite material air duct structure can maintain the normal operation under the limit overload working condition and meet the overall strength and stiffness requirements of the structure.