The El Niño-Southern Oscillation (ENSO) is the strongest signal in the tropics on the interannual time scale, and it can exert substantial influences on the weather and climate over many parts of the globe. Besides the well-known air-sea interaction and oceanic dynamical processes within the tropics, studies indicated that atmospheric forcings over the extratropics are also important in forming and maintaining the ENSO variability. In this talk, Shangfeng Chen will report that the significant impacts of the Arctic Oscillation (AO),the first leading mode of atmospheric variability over the extratropical Northern Hemisphere (NH), in spring on the subsequent ENSO via inducing anomalous westerlies over the tropical western Pacific. His talk includes:1) physical process for influence of the spring AO on the winter ENSO; 2) interdecadal change in the spring AO-ENSO connection and the related mechanism; 3) performances of the CMIP5 models in simulating the AO-ENSO connection.