To deal with the complex load conditions, diverse constraints and time-consuming problems faced during the design of the modular reconfigurable unmanned aircraft vehicle (UAV), taking the modular reconfigurable UAV in which different wings can be changed by using a common fuselage to meet different flying missions as the research object, different wings’ bending moment constraints application methods are studied in depth. A simultaneous multi-configuration optimization technique considering the wing’s front and back bars’ bending moment constraints is proposed. A typical modular reconfigurable UAV’s wing structure is designed and optimized by using the proposed method. Compared with the design results obtained by using the typical two traditional optimization formulations, the proposed technique is proven validate and convergent. And this method has some value in the practical engineering fields.