In this paper, aeromechanical analysis of wind turbines is presented. The distinctive feature of this paper is the use of frequency based non-linear harmonic method which is an efficient computational method to study unsteady periodic flow and aeroleasticity of turbomachinery applications, and extensive validation of the non-linear harmonic method against conventional time domain solution methods. This paper is an extension of the authors’ previous work which analysed the aerodynamics of the MEXICO (Model Rotor Experiments In Controlled Conditions) Experiment wind turbine. Aeromechanical analysis of the MEXICO-Experiment wind turbine as well as 1.5 MW wind turbine are conducted in this study. Both conventional time domain solution method and non-linear harmonic method are used, and compared to each other for validation and verification of the non-liner harmonic method. Using the same numerical set-up for each method demonstrates the differences and capabilities of each solution method, and their computational expenses. Finally, this paper concludes with how the aeromechanical analysis of large wind turbines can be performed effectively and efficiently using the non-linear harmonic method.