Abstract: All-vertical-piled wharf is a new type of high-pile wharf suitable for offshore deep sea. However, its bearing behaviors, failure modes and design and calculation methods are quite different from those of the traditional one. The purpose of this paper is to carry out researches so as to solve the above problems. By use of the 3D elastoplastic finite element model for the all-vertical-piled wharf and soil foundation based on ABAQUS, the bearing behaviors and failure modes under horizontal loads are studied. It can be concluded that when the all-vertical-piled wharf in offshore deep water is under the horizontal loads, the plastic failure of pile foundation is the key to the buckling damage, while the bearing capacity of foundation soil is not a decisive factor. After these analyses, a simplified calculation method for the horizontal bearing capacity is established based on P-Ycurves. The internal force and deformation at any position of piles can be calculated by means of this method. Moreover, the simplified method is suitable for both large and small displacements. The “plastic hinge” is used as the criterion of horizontal bearing capacity in the simplified calculation method. In comparison with the finite element model, the proposed method is proved to be reliable.