A design study aimed to optimize a composite wing in an aeroelastic way was presented using genetic algorithm and genetic/sensitivity-based hybridalgorithm. In order to increase the search efficiency of the above-mentioned two algorithms, a set of methods was put forward to fix primary and secondary design variables followed by adjusting the design variable domain on the basis of design variable importance in terms of their sensitivity. Results demonstrate that the size of design variable domain had direct effects on the search efficiency of genetic algorithm and genetic/sensitivity-based hybrid algorithm, especially when the former was used. Therefore, the search space should be reduced to be as small as possible if an enough amount of excellent feasible solutions in design space could be ensured. Results indicate that the method to adjust the size of design variable domain on the basis of sensitivity has proved to be of fairly practical success, which can not only remarkably increase the search efficiency of genetic algorithm and genetic/sensitivity-based algorithm, but also strengthen the capability of the two algorithms to discriminate the feasible field.