The relationships between Arctic Oscillation (AO) and East Asian cold winter have been comprehensively investigated during the last decade.More than that, it is suggested that most of the extreme phases of AO can be attributed to the downward propagation of Northern Annular Mode (NAM) from the stratosphere, which might be further modulated by tropical thermal forcing, like ENSO, and polar thermal forcing, like summer-to-autumn Arctic sea-ice coverage.