Aiming at the problem of boundary condition simulation of pile shoe of deep-water jack-up platform, taken a 300 ft (1 ft=0.304 8 m) jack-up platform as an example, the finite element software ANSYS is used for the static analysis and ultimate bearing capacity analysis, the influence of the conventional hinged support and elastic foundation constraints on the pile leg strength of the jack-up platform is compared, and the influence of different pile-soil boundary conditions on the ultimate bearing capacity and failure mode of the pile leg is further explored. The results show that: the elastic foundation constraint can effectively reduce the influence of p-Delta effect and significantly reduce the effective stress under corresponding working conditions, the stiffness of the pile leg calculated under this constraint method is greater, and the pile leg will enter the plastic stage first; the hinged support constraint is too conservative; the failure modes of the pile leg under the two boundary conditions are also quite different. The research can provide reference for the design of the jack-up platform.