Abstract: This paper investigates the dynamical mechanism and influencing factors of mode localization in wind rotor due to the blade damage. Firstly,the dynamical mechanism of mode localization is revealed from the perspective of eigenvalue,and it is found that the essential cause of modal localization is the existence of closely spaced modes in structures. Then,the finite element model of NREL 5 MW wind turbine rotor is established,and the effects of blade mistuning,modal order,and mistuning position on the model localization of the wind turbine rotor are analyzed. Numerical simulation results indicate that damage mistuning of a single blade can cause significant variations in vibration modes of the wind turbine rotor,triggering mode localization. And the significance of the investigation is that the mode localization will aggravate the blade damage and potentially cause fatigue damage of the blade in some modes. Therefore,it is necessary to consider the effect of mode localization on the dynamic characteristics of wind turbines during wind turbine design.