The methodology to adaptively change the configuration of an airfoil using a shape memory alloy (SMA) thin film actuator to improve aerodynamic performance is numerically demonstrated. To predict the thermomechanical behaviors of an SMA thin film, a 2-D incremental formulation of the SMA constitutive model is developed. By implementing a numerical algorithm of the SMA thin film, the interactions between the airfoil structure and SMA thin film actuator are investigated. Airfoils with either a plain flap or a slotted flap are considered and their aerodynamic characteristics are compared with those of the airfoil actuated using the SMA thin film actuator. Furthermore, the effectiveness of the airfoil actuated by SMA thin film to enhance the aerodynamic performance is discussed.