Plasma actuator is one of the active flow control equipment that is being developed in recent years. In this study, numerical analysis is used to obtain optimization of plasma actuator that placed on airfoil at 0.21c. This numerical simulation executed at 3 (three) variations of Reynolds number, 35,000, 100,000, and 200,000 The plasma actuator was installed on an NACA 4415 with 100 mm chord length (1:1 scale) and magnetic induction (magnetohydrodynamics) is applied. The calculations of aerodynamics force, such as lift force and drag force was held to investigate the most optimal performance of plasma actuator. The results of this numerical study show that by placing plasma actuator around 0.21 from chord line, obtaining optimization in decreasing of drag coefficient and increasing of lift coefficient on 35,000 of Reynolds number. Where plasma actuator is proven to be most effective way for reducing drag coefficient at angle of attack of 15°with a percentage decrease of 15.01%. While the largest increasing of lift coefficient, 17.15% was occur at 9°angle of attack.