Abstract:The monopile foundation is widely used in the construction of offshore wind power due to its simple structure and easy installation. However, there is no unified method about how to determine the horizontal ultimate bearing capacity of a monopile foundation. Therefore, this paper summarizes the existing three types of determination methods, which are limit equilibrium method, p-y curve method and qualitative method, and studies the difference between the horizontal ultimate bearing capacity calculated by different methods, combined with the test cases. The results show that the results obtained by different methods are quite different, and the maximum gap can reach 38.84%. Since there is no uniform method and the results obtained by different methods vary greatly, further research is needed to determine the ultimate horizontal bearing capacity of the monopile foundation.