To enhance the maneuverability of the selected aircraft model, a standard genetic algorithm (GA) is used as an optimization method for the preliminary design of the leading-edge extension (LEX) layout. The aerodynamic loads and the maximum lift coefficient of the complete aircraft configuration (fuselage wing tail) are computed by using the modified three-dimensional low-order panel method in conjunction with the semi-empirical formulas of DATCOM. Results show that the lift coefficient increases approximately 20.5 %-15.3 % for Mach number 0.4-0.8 and 6.8 % for Mach number 1.2, and its maximum value approximately 9.5 %-15.0 % for Mach number 0.2-0.95 when LEX is installed. A 6.6 %-8.0 % gain at altitudes of 1-5 km on the turn rate maneuverability and the corner speed have been achieved in the subsonic regime.