High power generating cost is a important problem in a sustainable energy. In order to reduce the cost for the power generation, passive power control using elastic turbine blade made of composites is adopted. In this study, the performance evaluation system with fluid-structure interaction analysis and water tank tests has been developed to design the passive power control property and evaluate its performance. First, we made rigid blade models and elastic blade models to compare the calculated deformation by fluid-structure interaction analysis. The deformation of blade is measured by a noncontact optical stereo camera. Consequently we confirmed that we can predict the deformation with fluid-structure interaction analysis. By using some numerical optimization methods, we try to design elastic turbine blade in actual sea condition.