In the curved surface molding of automobiles’ covering components, large amounts of data should first be sampled, and be fitted to curves with the conventional data-fitting method. Then the curves are connected to face and given corresponding molding processing, and the required effect of the curves is being smooth and accurate. The conventional data-fitting method is improved in this paper considering practical application, and the accuracy is increased with the same amount of sampling data. In practical application, this method can lessen labor intensity by decreasing measured data amount, which increases work efficiency and doesn’t affect the curve fitting accuracy. So it has good engineering application value.