A wing through which fluid flows will form a three-dimensional separation caused by two interacting boundary layers. This separation will result in secondary flow which can be detrimental to airfoil performance. Until now, aircraft often use a slotted type flap that can prevent separation so that it can reduce the value of less resistance. This study will examine the performance and aerodynamic characteristics of the modified single-slotted flap on the Cessna 208b Grand Caravan wing. The method used is a numerical simulation with CFD software in the form of ANSYS. The test object is a modified Cessna 208b Grand Caravan wing with a single slotted flap with a flap angle (α F ) of 0°, 15°, and 30°to determine the effect of aerodynamic performance. The angles of attack reviewed are α = 0°, 2°, 4°, 6°, 8°, 10°, 12°, 14°, 15°, 16°, 18°, and 20°. The fluid flow used is air with a cruising speed of 96 m/s above sea level in stable conditions. The simulation results show that the addition of flap angle modification on the Cessna C208b Grand Caravan wing can affect both performance and aerodynamic characteristics. At a speed of 96 m/s, increasing the flap angle can decrease the value of C L /C D at high angles of attack. However, the addition of the flap angle can provide a better C L /C D value at low angles of attack.