Based on the Nanjing Institute of Meteorology/Coupled Ocean-Atmosphere Model System(NIM/COAMS),the capability of the model in simulating inter-annual variations is verified in this paper.The 50-year integration shows that the model can simulate the main annual variation of the interface between atmosphere and ocean,and the main character and evolution of the ENSO cycle with a period range of 3-5 years in tropic Pacific.The simulation has demonstrated that the model has the capability for simulating the annual variation and air-sea coupling characteristics.These abilities come from the coupled scheme named flux reanalysis coupling scheme(FRAC) which is able to avoid the influence of climatic mean fields,thus enhancing the simulating ability of the annual variation of the model.