The tuned mass damper (TMD) is introduced to the field of structural control of wind turbines. Taking the 5MW offshore wind turbines as a research case, the parameters of TMD are optimized via both theoretical analysis and numerical simulation. In the theoretical analysis, to grasp the key factors of the wind turbine in the aspect of structure dynamics, the turbine with TMD system is simplified with three degrees of freedom in longitude direction. The influence of the parameters of TMD such as damper ratio, frequency is investigated through frequency domain analysis of the transfer function between the total thrust force and displacement of the wind turbine. Based on the theoretical analysis, the TMD is further optimized using numerical simulation under a certain wind condition via the program FAST-SC, in which a more complicated model of the wind turbine is established. The results show that TMD can obviously affect the characteristics of the vibration and load of the wind turbine. By optimizing TMD, the vibration and load of the wind turbine can be substantially attenuated. For further applying the structural control of wind turbines using TMD, the performance of TMD is verified under some standard wind models from GL2010 including EOG, NWP, EWM, ECG, EDC, via FAST-SC. The result shows that the vibration and load suppressing capacity of the wind turbines by TMD system can reach above 10% in some operating cases, which make great significance for the structure control of wind turbine.