Airfoils are widely used in fluid machinery, and airfoil stall is an important reason for equipment safety hazards. Biomimetic leading-edge protuberances are considered a potential means of stall control. In this study, the Transition SST turbulence model was employed to carry out a numerical simulation on the NACA 634-021 airfoil. The airfoil consists of a leading edge with 30 protuberances, forming an unusually wide wing. This configuration has never been previously investigated and is novel to this research. The results showed that the bio-inspired airfoil reduced the maximum lift coefficient by 14.2% and advanced the stall angle by 8°. The biomimetic airfoil exhibited excellent performance after stall. The maximum lift coefficient increased by 25.1% and the lift-to-drag ratio increased by 21.8%. At high angles of attack, due to the influence of the protuberance peak attachment flow, the suction surface flow field formed an alternating distribution of expansion and contraction. This validated the correctness of the conclusion that the suction surface flow field of the biomimetic airfoil exhibits periodic distribution at low angles of attack and non-periodic distribution at high angles of attack. Biomimetic airfoils have advantages in working with large changes in the angle of attack. This provides a theoretical basis for the application of biomimetic protuberances in vertical axis wind turbines and fixed-wing drones.