In this paper, we developed a optimal design system to optimize composite shell structures using genetic algorithm and expert system. The objective of the optimal design was to find designs that minimize weight of the structures and satisfy the design rules specified by the user. Buckling analyses of the composite shell structures were done to estimate buckling loads. Some example problems were selected and optimized with the developed system. And a GUI-based integrated design and optimization program, I-DOTCom was developed and introduced at the end of this paper.