The characteristics of the turbulent flow around an airfoil attached to a slat and a flap under the effects of wavy ground were numerically investigated using the k − ε turbulent model at the Reynolds number of 17 x 105 at various angles of attack (AoA) and altitudes (h/c, where h and c are the spacing between the leading egde and wavy wall and the chord line length, respectively). The objective of this study is to elucidate the impact of AoA and altitude on hydrodynamic coefficients and the flow structure of a multi-element airfoil. This will be achieved by analyzing pressure distributions, turbulent kinetic energy, and plotting drag (Cd) and lift (Cl) coefficients. A significant change in Cd and Cl is observed, depending on the AoA and h/c ratios. Especially when the AoA of slat and atitude increases, Cl decreases remarkably while Cd rises due to the higher flow resistance. The results provide a thorough understanding of the aerodynamic characteristics of the airfoil traveling over such terrain as wavy ground. Moreover, this study case is a typical reference for the aviation industry to improve their next aerodynamic design.