NCAR's community atmospheric model v3.0(CAM3.0) is used to explore the possible external forcing mechanism of North Pacific eastern-pattern storm track(EPST) in winter,when the storm track often has its strongest center located east of 160°W.This paper mainly focuses on the effect of positive(P) and negative(N) sea surface temperature anomaly(SSTA) in the middle-east equatorial Pacific(EP) and the Kuroshio Current(KC).Results show that EP-N SSTA has significant meaning for the emergence of EPST.The EP-N(P) and KC-P(N) SSTA can lead to the eastern(western) pattern of the storm track.The activity of storm track in eastern North Pacific may be caused by the enhancement of low level baroclinicity.Specifically,when there is the eastern(western) pattern,the westerly jet in eastern North Pacific,as well as the eddy baroclinicity,the transportation of synoptic-scale heat and momentum,and the feedback between eddy waves and mean flow increase(decrease),and v.v..Compared with EP,the atmospheric responses to SSTA in KC are more local and asymmetric with respect to the sign of SSTA,and KC-N SSTA mainly influences the entrance area of the storm track.