In the strong atmospheric baroclinic zone of the North Pacific at mid-latitude,the spread activities of synoptic-scale eddy are frequent,which maintain atmospheric circulation through the moisture,momentum and energy transport.In order to further study the relationship between the occurrence and development of synoptic-scale eddy and large-scale circulation,this paper selected 114 strong and 87 weak days of the western developing pattern synoptic-scale eddy (WSE) by using the reanalysis data from 1981 to 2013,and gave the variations of dynamic and thermal forcing caused by the WSE anomalies.Meanwhile,it analyzed the interaction between the WSE and mean flow from the perspective of energy transformation and the relationship between the WSE and the Western Pacific (WP) teleconnection pattern.Results show that the WSE affects mean flow through dynamic and thermal forcing.The dynamic forcing mainly makes the westerly currents over the mid-latitudes of North Pacific accelerate and move northward,while the thermal forcing weakens atmospheric baroclinicity over mid-latitudes.Meanwhile,the strong WSE is beneficial to increase the conversion of baroclinic available potential energy to eddy kinetic energy and eddy kinetic energy to mean flow in the lower troposphere over Northwest Pacific,and to increase the conversion of mean flow to eddy kinetic energy in the upper troposphere over mid-latitudes.In addition,the WSE has a certain effect on maintaining the negative phase of the WP teleconnection pattern through its interaction with the mean flow.