Abstract: Aiming at the problem of amplitude attenuation of wind turbine blades caused by non-linear characteristics and environmental impact,a dynamic model of wind turbine blade dual-excitation resonance fatigue loading system is established.The dynamic equation of the excitation loading system is solved by averaging method,the vibration characteristics of the system are analyzed,and an adaptive sweep frequency control method for fatigue loading is proposed.Based on the phase difference between excitation force and displacement response detected by phase discrimination method,the relative relationship between phase difference change and blade natural frequency change is analyzed,and the resonance frequency tracking controller of the system is designed.Then the simulation model of the controller is established by using Matlab/Simulink to simulate numerically,and the effectiveness of the controller and the robustness of the control system is analyzed.The results of fatigue loading test of megawatt wind turbine blades under double excitation show that the controller can maintain the amplitude error of blades,realize resonance fatigue loading with blade,and the adaptive frequency sweeping control method is reliable and effective,and the accuracy and efficiency of fatigue tests is improved.