Efficiency and stability of forward problem are important in structural optimum design. A real-time algorithm, called inversion reduced-basis method (IRBM), is applied to solve the forward problem in this paper. IRBM is introduced theoretically. Taking a truck frame as an example, results computed from IRBM are obtained. In the optimization process, a modified micro-genetic algorithm (μGA) is adopted to get the global optimum. In the structural reanalysis, IRBM is used, which greatly shorten the design cycle and improve work efficiency.