A numerical process, which consists of free or force vortex motion, boundary element methods and optimization methods, was developed to calculate the design parameters of an axial flow fan. Rotational speed, tip and hub diameters, and number of blade were used as the input data. Stagger angle, radial varation of the blade angles, was calculated with this numerical process. Sum of the difference of the stagger angle for numerical solution and that for current design was minimized by using the optimization methods. Parameters of the computational solution, including lift and drag of an aerofoil, inlet flow angle and velocity, outlet flow angle and velocity, and variation of axiaI velocity in the radial direction, were calculated to investigate the current product of axial flow fan.Three cases were run to validate the numerical solutions. Case A and case B were the Valeo's current products; case C was the Valeo's prototype fan. Computational result of stagger angle was compared with the stagger angle obtained from these Valeo's products. Agreement of the comparison was good. This numerical approach could be applied to investigate the parameters for any axial flow fans.