Subsea wellhead connector is an important equipment for offshore oil and gas exploration and development. The sealing performance of VX gasket directly affects the safety in the whole subsea production system. In order to solve the problem of inaccurate modeling caused by two-dimensional axismetrical model used in the analysis of subsea wellhead connectors, a three-dimensional finite element model of subsea wellhead connectors was established based on ABAQUS software. The sealing performance of VX steel gasket under preloaded and working conditions was analyzed, and the influence of material properties and cyclic internal pressure on the sealing performance was discussed. The results show that under preloaded and working conditions, the connector has desirable sealing performance, and the surface contact stress of VX gasket fluctuates in the circumferential distribution. The influence of material on sealing performance is mainly reflected in the yield strength, and the contact stress increases with the increase of yield strength. Under the action of 0~155.25 MPa cyclic internal pressure, the sealing performance of the connector decreases gradually. Therefore, the connector cannot be used repeatedly. The research results can provide theoretical support for the production and application of VX gasket.