In this article, a numerical investigation of the effect of simultaneous suction and blowing on an airfoil is studied to reduce the separation bubble. This investigation was done at Re=8.5×106 and the simulations are done by commercial Fluent software. First, the suction and blowing systems are used at different blowing and suction angles (30, 45 and 90 degrees) along with their location (distance ratio 0, 0.1, 0.2, 0.3, 0.6, 0.7 and 0.8) were investigated. In this study, the ratio of lift to drag, pressure coefficient, velocity and pressure contours were compared in different cases compared to the one with no slot, and finally the best state was determined. The results of this study showed that the suction on the leading edge and blowing on the tailing edge can improve the aerodynamic performance of the airfoil at an angle of attack of 17 degree. The best performance was the blowing at a distance ratio of 0.6C and suction at 0.1C, which increased the lift-to-drag ratio by 55%. Compared to the one without any slot.