Abstract: In order to solve the problem of wind turbine tower fatigue caused by the large mass of traditional pendulum tuned mass damper (PTMD), the pendulum tuned mass damper inerter (PTMDI) device and design method are proposed according to the characteristics of large wind turbine tower structures. The proposed guiding device integrates the three-parallel inerter system with the traditional PTMD device, transmits the reaction force of the inerter device to the lower part of the tower, thereby achieves the effect of ground-like inerter and realizes the lightweight vibration damping through the mass amplification effect of the inerter; the two-degree-of-freedom coupled dynamics model of the controlled wind turbine with the additional PTMDI is established based on the principle of virtual work, and the dynamic amplification coefficient as well as the branching-point resonance frequency ratio of the controlled wind turbine is derived. Based on the fixed-point theory, the optimal frequency ratio and damping ratio of the controlled wind turbine as well as the design method of the stiffness and damping of the inerter system are proposed, and the optimal design of the PTMDI is realized. The numerical example results using a 5MW wind turbine tower show that the proposed PTMDI can effectively reduce the acceleration response of the wind turbine tower by 78% even with an 80% weight reduction in additional mass, and it can improve the PTMD damping efficiency by more than 20%.