Abstract: To further improve the aerodynamic performance of airfoils, a bionic curved flap was proposed based on the trail fin profile of mako sharks. The aerodynamic performance and internal flow of the bionic airfoil were simulated using the SST k-ω turbulence model, and the effects of relative position and installation angle of the bionic flap were analyzed to obtain the optimal bionic flap airfoil with the best aerodynamics, which was compared to the Gurney flaps. Results show that after installing a bionic flap, its lift-drag ratio is significantly higher than the baseline; when the relative flap height remains unchanged, reducing the installation angle and increasing the distance between the flap and the trailing edge lead to an early airfoil stall onset. The aerodynamic performance of the bionic flap airfoil with reverse installation angle of 45° at the trailing edge is the best, and the lift coefficient is 5.9% higher than the Gurney flap airfoil before the stall. After arranging the bionic flap, the flow field tends to be complicated, and the position, quantity and size of vortices change.