The monopile of offshore wind turbines will bear horizontal static and dynamic loads generated by wind, waves, currents, and rotors during service period. Because of long-term cyclic loads, the bearing capacity of monopile will become deteriorated. Base on the combination method of model testing and finite element analysis, a study on the cumulative deformation and bearing capacity deterioration of monopile under cyclic loads was conducted in this paper. The study revealed the change laws of monopile about cumulative deformation and bearing capacity with the number and amplitude of cyclic loads. The cumulative deformation of monopile increased approximately as a power function with the increase of load cycles, while the bearing capacity decreased with the increase of load cycles. Moreover, the influence of bidirectional cyclic loads on the cumulative deformation and bearing capacity of monopile was more significant than that of unidirectional cyclic loads.