Mechanical properties of plain weave carbon fiber reinforced plastic (CFRP) composite were studied by static and fatigue experiments. The new Haigh diagram model was established by using Kriging interpolation method and Basquin formulation. The model can predict SN curves under random loading conditions. And those curves were used as constraints of optimization design. The surrogate modes of optimization object and constraint were established using optimal Latin hypercube design (OLHD) of experiment and Kriging model. The shell thicknesses of power battery pack of electric vehicle were obtained by genetic algorithm. The optimized results were verified through fatigue bench testing. The weight of optimized structure reduced 34.39%.