Wind turbines operating in unsteady and complex environments often encounter asymmetric and unsteady vortex flows on the leeward side of the blades, leading to airflow separation and dynamic stall. These issues significantly impact the aerodynamic performance and energy efficiency of wind turbines. However, there is a lack of research regarding the regulatory relationship between airfoil parameters, trailing-edge flap oscillation angles, and aerodynamic parameters. To address this research gap, this study employs a multi-block overlapping grid technique and a custom-programmed method to simulate active flow control on wind turbine blades by coordinating the motion of the main wing and trailing-edge flap during pitching oscillations. Aerodynamic parameters of airfoils were computed to investigate the impact of trailing-edge flap deflection direction, deflection amplitude, and other parameters on the wind turbine blade thrust, torque, and aerodynamic characteristics under deep stall conditions. An optimized aerodynamic performance curve of the blade was produced. The results show that when a deep stall occurred and the wind speed was low, the lift coefficient of the airfoil can be increased by approximately 23% with the amplitude α_amp1=40° and the same deflection direction; moreover, the tangential force and torque value on the blade concurrently increased. Adjusting the motion of the main wing and trailing-edge flap reduced the thrust and load fluctuation of the blade by changing the flap amplitude value. Additionally, the operation efficiency of the wind turbine improved. These results can provide a reference for the active flow control and application of wind turbine flaps.