The invention discloses a fitting method of blade surface data. The method comprises the steps of the fixing of centers and radiuses of intake and exhaust sides, the fixing of arcs in polynomial fitting blade body surface and blade surface, and the fixing of the maximum thickness value of the blade body surface. According to the method,The repeated computing amount and the computing time of designers are greatly reduced, the computation of the blade surface data is enabled to be accomplished in seconds, the whole bade development time is shortened by one third, the data accuracy and the jig design accuracy of blade surfaces are improved, the precision forging technology is improved, and the requirements of modern digital machining equipment are met. Blades machined through the fitting method is smooth in solid surfaces, the phenomenon of back which usually occurs in traditional blade bodies manually adjusted can not occur, the blade body profile line of a blade forge piece designed on the basis of the surface is smooth, a final die cavity is not required to be repeatedly repaired, and the forming quality of the blade forge piece is improved.