The design of a rotor blade requires comprehensive information of the particular wind-mill location. The design itself consists in determining the aerodynamic and geometric characteristics of the rotor blade (local chords, blade twist, airfoils).The blade design has to satisfy the design conditions, gain high aerodynamic efficiency and simultaneously take into consideration blade structural constraints (diameter, number of blades, revolutions). The paper deals with the design of aerodynamic characteristics of the rotor blade of a wind mill in a chosen design point. The design is specified for the rotor of the diameter 20.4 [m] and revolutions 0.728 [s-1].