In this thesis, aerodynamic design of 1, 5, 10, 25, 50, 100, 250 and 500 kW horizontal axis wind turbine generators has been performed. The design procedure starts with the design and analysis of airfoils done by programs of PROFOIL and XFOIL, respectively through which the structural, aerodynamic and aeroacoustic principles have been taken into consideration. Then, the performance parameters of designed profiles were inputted to the constructed modified blade element momentum theory (BEM) code together with the main design parameters in order to obtain 3D blade geometry. The code is validated using MIE wind turbine with a rated power of 8 kW. The generated blade geometries are then analyzed using commercial computational fluid dynamics CFD code Numeca FINE™/Turbo and the velocity and pressure distributions around the blade have been visualized, separately. Moreover, the power coefficient, Cp was calculated and the power curves of the designed wind turbine rotors were drawn.