The existence of the wind turbine rotor is equivalent to a vortex system composed of three parts: a central vortex along the rotor axis, a bound vortex on the blade, and a helical vortex sheet departing from blade trailing edge.So the induced velocities which are used to modify the relative velocities (around the airfoil) to the wind turbine blade can be given by means of Biot-Savart theorem.But the above-mentioned results only result form the potential theory in the fluid mechanics and have nothing to do with the blade configurations, the airfoil performances for the wind rotor blade and changeble circulation along the wind rotor blade axis are introduced to combine with the potential therory in order to obtain more accurate and practical results.Bsased on the idea, the optimization numeric methed to design the wind rotor is presented and the validity of the method is also proved by comparing with other ones in designing a model wind rotor.