Subsea wellhead and wellhead connectors usually utilize metal sealing gaskets to establish a sealed channel between production operation and the external environment. In order to study the structural characteristics of subsea wellhead sealing gaskets and the response characteristics of different gasket structural forms under environmental loads, this paper focuses on the 18-3/4 in(1 in=25.4 mm) 10 K wellhead specifications. Using the finite element analysis method based on ABAQUS, the optimal structural parameters for the commonly used VX sealing gasket were determined. The gasket structure was then optimized according to its sealing characteristics, and the load response analysis was conducted for various gaskets structural forms. The results show that the optimal sealing cone angle θ for the VX sealing gasket is 22.7°~22.8°, and the optimal cone top diameter D is 507.8~508.4 mm. The VAX sealing gasket can significantly improve the contact stress and stress distribution on the sealing surface compared with VX sealing gaskets, although its load-bearing capacity is weaker. The annular groove on the sealing surface can effectively enable the sealing gasket to establish primary and secondary dual seals and increase the contact width of the primary seal, but do not improve gasket’s load capacity. Within the load capacity range of the wellhead connector, environmental loads have minimal impact on the sealing performance of the sealing gasket.