In order to solve the leakage problem of the high pressure selfsealing flange under the given environment,the 3D model of high pressure selfsealing flange was established by using SolidWorks.The influences of the dimension of flange seal ring,flange rigidity and bolt pretension on sealing performance were analyzed by using ANSYS and MATLAB from the view of the stress distribution uniformity of flange sealing ring.The results show that the external diameter of the sealing ring has a significant impact on the stress distribution uniformity of the flange seal ring,and there is an optimum range of the external diameter of the seal ring.Considering the compactness and stress distribution uniformity of the whole flange system,the optimum external diameter of the seal ring of 4715 mm flange system is 56.9 mm.The flange rigidity and bolt pretension have no significant effect on the stress distribution uniformity of the flange seal ring.