Single tuned mass damper (STMD), being an effective vibration absorber, is generally installed at the top of a flexible structure for vibration control. Due to the limited space, the design and installation of the STMD may be greatly restricted, especially for slender structures such as wind turbine towers. More importantly, the effect of STMD has been proved to be limited for the involvement of multiple modes. For the reasons above, the multiple tuned mass damper (MTMD) has been proposed. In the present work, the constrained parameter optimization of the MTMD system designed for the wind turbines is performed, based on the initial configuration given in advance. The transfer function from the ground motion to the response of the wind turbine tower is derived by means of modal superposition. A proper objective function is developed by comprehensively considering displacement, acceleration as well as based reaction forces. The genetic algorithm (GA) is employed for searching the optimal design parameters of the MTMD system. A wind turbine model is adopted as an example, and the working efficiency of the MTMD system is finally verified by comparing with the classical Den Hartog's formula. Results reveal that the designed MTMD system is feasible for control of multi-mode vibration, having potential value for broader practical applications.