Abstract: Arctic Oscillation (AO) is the dominant mode in the atmospheric circulation variability over the extra-tropical Northern Hemisphere. El Niño-Southern Oscillation (ENSO) is the primary mode in air-sea interaction over the tropical Pacific on interannual timescale. Variations of AO and ENSO exert substantial infl uences on the weather and climate anomalies over large areas in the globe. This paper reviews the studies of the infl uence of AO on ENSO, to improve our understanding the physical processes in the infl uence of extratropical atmospheric circulation on the tropical climate. It was found that the AO in spring has a signifi cant infl uence on the ENSO events in subsequent winter. Interaction between synoptic scale eddy and low frequency mean fl ow over North Pacifi c plays a key role in the formation of the spring AO-related westerly wind anomalies over tropical western Pacifi c. The connection between the spring AO and subsequent winter ENSO experiences a signifi cant interdecadal change around the early 1970s. This interdecadal change is closely related to the interdecadal change in the storm track intensity over North Pacifi c. The infl uence of the spring AO on the subsequent winter is asymmetric. Spring AO can exert signifi cant infl uences on the following winter ENSO events only in its positive phase. Spring AO has a signifi cant modulation effect on the linkage between previous winter North Pacifi c Oscillation and the following winter ENSO. In addition, the AO in November can exert signifi cant infl uences on the sea surface temperature anomalies over tropical central-eastern Pacifi c in the following spring and summer. The intensifi cation of the North Pacifi c storm track activity plays an important role in determining whether the variability of AO can exert infl uences on the subsequent SST anomalies in the tropical central-eastern Pacific.