The surface conductor is a critical structure in deepwater drilling operations, supporting the subsea wellhead, lower casing strings, and subsea blowout preventers. Researching the factors influencing the load-bearing capacity of the surface conductor, as well as the relevant theories and field practices that impact the stability of the subsea wellhead, is of paramount importance. This paper investigates the influence patterns of various factors on the stability of the subsea wellhead and the load-bearing capacity of the conductor during operations. It establishes a theoretical model and calculation method for the axial load-bearing capacity of the surface conductor applicable to deepwater drilling. By considering changes in fluid density, a calculation method for the variation of axial loads on the subsea wellhead during surface cementing operations is proposed. The most critical operating conditions for axial forces on the wellhead are identified, and measures to enhance wellhead stability are suggested. The study concludes that the properties of shallow seabed soil, the load-bearing capacity of the surface conductor, jetting operation parameters, and changes in axial loads on the subsea wellhead caused by variations in fluids inside and outside the cementing process are the primary factors leading to instability or subsidence of the subsea wellhead. The research results can provide a reference for deepwater surface drilling and completion operations.