The automotive door has a large finite element model in analysis and many design requirements such as stiffness, natural frequency, side intrusion, etc Thus, various related governing equations should be solved for systematic analysis and design Because each governing equation has different characteristics, it is almost impossible to solve them simultaneously Instead, they are separately handled and the analysis results are incorporated into the design separately. Currently, the design is usually conducted by trials and errors with engineering intuition in design practice In this research, MDO methods are proposed to solve the problems that share design variables in disciplines The idea is from the Gauss-Seidel type method for multi-discipline analysis The developed methods show stable convergence and the weight of the door is reduced by fifteen percent.