The multidisciplinary design optimization (MDO) of wing box is transformed into the issue of multiconstrained optimization (MCO) of wing box with all relevant sizing requirements for structural stress, stability,aero-elastic behavior. Deflection and manufacture are treated as the constraints of the sizing optimization. All constraints are linked with the design variables and written into the process of optimization by TCL/ Tk toolkit based on Hyperworks platform. A MCO model of wing box is developed after a FEM model. The MCO method has been successfully applied to a trunk liner wing box sizing and a 7.4% weight-saving result has been obtained with much shorter iteration, which confirmed its validity.