With the development of offshore wind farms expanding towards the deep sea, the applicability of the large-diameter monopile is confronted with some great challenges. The exploration and research of new type foundation is very important and meaningful. Based on the ABAQUS software, it is compared that the bearing capacities of large-diameter monopile, pile-plate composite foundation, and pile-bucket foundation in saturated clay under vertical loading V, horizontal loading H, and bending moment M. The results show that the bearing capacities of two composite foundations is obviously better than the bearing capacities of the monopile foundation. The vertical bearing capacity, horizontal bearing capacity and bending bearing capacity of pile-plate composite foundations increase exponentially with the additional plate diameter increasing. The vertical bearing capacity and bending bearing capacity of pile-bucket foundations increase with the buried depth of bucket structure increasing, and then the increasing trend is gradually weakening to the parallel line. And the horizontal bearing capacity of the pile-bucket foundation has a linear relationship with the diameter and buried depth of the bucket structure in the soil. Under the composited loading conditions of V-H and V-M, the failure envelope spaces of the two composite foundations are larger than those of the monopile, then the bearing performance of two composite foundations is significantly better than the monopile. The research results provide a reference for the selection and optimization design of foundations offshore wind turbine foundations.