A numerical method was developed to establish a procedure for an axial flow fan design. Theory of free/force vortex motions, boundary element methods and optimization methods were applied to conduct this process. Rotational speed, ambient temperature and pressure were used as the input data; and tip diameter, hub diameter, number of blade, flow rate, static pressure, and vortex motion were initially guessed and employed to compute the design parameters. These design parameters included lift and drag of an airfoil profile, inlet angle and velocity, outlet angle and velocity, and variation of axial velocity in the radial direction. The optimization of tip diameter, hub diameter, number of blade, chord, and stagger angles at different radii were calculated as the numerical results.Computational solutions of the stagger angles in the radial direction were compared with those of the Valeo's current products. Agreement of the comparison of the stagger angle is reasonable.