To meet the usage requirements of the wellhead mandrel-type tube hanger of 175 MPa ultra-high pressure, four specially shaped metal sealing structures are selected as the research objects in this paper. The mechanical properties of different metal sealing structures are calculated, respectively, by using finite element software and binary regression analysis software. It was found that the mechanical properties and contact pressure fluctuations of X-shaped and straight U-shaped metal seals were relatively large, and the sealing width was relatively small among the four types of special-shaped metal seals. The mechanical properties and sealing performance of ball-drum-type metal seals and elliptical U-shaped seals were relatively stable, and the contact width was relatively large. For the single U-shaped sealing structure, the optimization rates of the maximum contact pressure and the minimum equivalent stress reached 11.63% and 10.63%, respectively. For the double U-shaped structure, the optimization rates of its maximum contact pressure and minimum equivalent stress both exceed 12%. The tests showed that the metal sealing structure met the pneumatic sealing requirement of 175 MPa. These results provide theoretical guidance for the research and design of a new type of ultra-high-pressure mandrel oil and casing hanger with a long service life and high reliability.