As an aircraft stalls under high angle of attack, airflow is separated from the wing surface, resulting in drastic lift loss and drag increase. Consequently, the performance of the wing is impaired, jeopardizing the safety of the aircraft. To mitigate this problem, a common practice is to install vortex generators on the upper surface of the wing. They function by introducing high-energy vortices into the sluggish boundary layer, thus delaying the separation to a higher stall angle. They can effectively improve lift during take-off and landing. In this study, several important parameters of vortex generators are optimized to produce the maximum lift at a high angle of attack. The results are very useful for the design of vortex generators to improve the safety of an aircraft.