In order to solve the problems of narrow sealing width and short service life of the circular flange surface of the oilfield wellhead sealing device,circular,elliptical,and conical flange surfaces were designed,and the sealing performance and service life of different linear flange surfaces were studied.It is found that under the same structural size and excitation load,the sealing width and structural life of the cone surface are much better than those of the circular and elliptical surfaces,but the long contact width leads to the contact stress of the cone surface can not meet the requirements of the working conditions.An analysis model with the conical sealing ring as the optimization object was established,the sensitivity and value range of each structural parameter were determined by single factor analysis.The contact stress of the upper and lower sealing surfaces was taken as the optimization goal,the first-order and second-order response models of the significant factors and contact stress were obtained.The optimized contact stress reaches the sealing requirements and increases by 21.7% and 8.2% respectively,and the maximum variance is only 30% of the curved surface,which can obtain a reliable structural life.