Abstract: Compared to the current traditional bucket foundation,large-scale bucket foundation with cover-load-bearing mode has been paid more and more attention because of its special load-bearing mode and its better bearing capacity.As a new type of foundation for offshore wind turbines,it plays an important role to evaluate the ultimate bearing capacity and establish the failure envelopes of the foundation and analyze the load-bearing characteristics in the research of security and stability during the process of structure design and practical application.In this paper,the general-purpose finite element analysis package ABAQUS is used to conduct three-dimensional numerical analyses.Based on the displacement control process,the Swipe test loading method and the combined load-displacement searching method,the bearing capacity behavior of two typical forms of 5MW large-scale bucket foundation for offshore wind turbines are analyzed and compared with elasto-plastic method.The results show that the ultimate bearing capacity of arc-type foundation is larger than straight line-type by 6%-8% under the single load; arc-type foundation demonstrates better load-bearing properties than straight line-type because of its wider 3D failure envelope under combined loading.Meanwhile,the failure mechanism of two foundations is explored,which can provide corresponding referential resources for selection of type and the optimization design for this foundation.