Aimed at the problems that it is difficult to judge the setting position of the conventional hanger seal and the defect of the sealing structure,the mechanical calculation of the seal performance of the conventional casing hanger seal structure was carried out.The influence factors on the seal width and contact pressure of the contact surface of the conventional seal structure were studied,the working mechanical mechanism and the seal structure were simulated,and the problems existing in the existing sealing structure were found out.Based on the design concept of elliptical metal seal structure,combined with the existing metal seal structure,a large diameter mandrel casing hanger with conical multi curved surface elliptical all metal seal structure was developed.The indoor high-pressure gas seal test shows that the designed metal seal structure is reliable,which lays a foundation for the field application of all metal mandrel hanger.