The wind turbine blades are exposed to the adverse high-altitude environment for a long time and are very prone to mass imbalance failure,which has a significant influence on the stable and reliable operation of the wind turbines.The previous blade mass imbalance studies mainly focus on the analysis of wind turbine power and tower.Foundations with foundation-ring are widely used in wind turbines,which are prone to damage under cyclic loading.Therefore,a service performance assessment model of wind turbine foundation considering blade mass imbalance failure was established based on blade element momentum theory.The additional load caused by the mass imbalance blade on the foundation was calculated using the analytical method.Combined with the equilibrium condition and continuity condition,the large finite element software ABAQUS was selected to simulate the influence of the blade mass imbalance failure on the wind turbine foundation stress,fatigue life,and concrete crack development.The results show that the mass imbalance blade in the horizontal direction has the greatest impact on the fatigue life of wind turbine foundation,blade mass imbalance failure will accelerate the foundation concrete damage and increase the level of the foundation ring,which in turn reduces the reliability of the overall service of the wind turbine foundation.Furthermore,it is recommended to maintain the turbine operation by reducing the rotational speed and to monitor the blade mass loss ratio regularly when small blade mass imbalance damage occurs in the turbine.