Modern horizontal axis wind turbine blades are long, slender, and flexible structures that can undergo considerable deformation, leading to blade failures (e. g., blade-tower collision). For this reason, it is important to estimate blade behaviors accurately when designing large-scale wind turbines. In this study, a numerical analysis considering blade torsional degree of freedom, geometric nonlinearity, and gravity was utilized to examine the effects of these factors on the aeroelastic blade behavior of a large-scale horizontal axis wind turbine. The results predicted that flapwise deflection is mainly affected by the torsional degree of freedom, which causes the blade bending deflections to couple to torsional deformation, thereby varying the aerodynamic loads through changes in the effective angle of attack. Edgewise deflection and torsional deformation are mostly influenced by the periodic gravitational force on the wind turbine blade.