A method of tooth profile error measurement and evaluation is given on the basis of the definition of profile error and the generating method of involute gear.The coordinates of points in the actual tooth profile are obtained by using three-coordinate measurement machine,and the practical tooth profile is fitted with cubic spline function in AutoCAD.Then the tooth profile error of gear is obtained through comparison the actual value with the theoretical value of Δg according to the principle of generating method.The feasibility of this method is verified by measurement experiment.Compared with the traditional measurement method of profile error,the method has some advantages,such as high efficiency of data acquisition,simple evaluation method and accurate measurement results.