From 1979 to 2016,Northeast China experienced 259 summer extreme high temperature (EHT) events.This study uses the hierarchical clustering method to classify the 500 hPa geopotential height anomalies of those EHT events and investigates the circulation evolution characteristics of different types of EHT events and their relationships with sea surface temperature (SST) anomalies in the North Atlantic.Results show that summer EHT events in Northeast China can be divided into three types,namely the westerly-type,blocking-type and wave-train-type with the occurrences of 113,89 and 57,respectively.The main feature of atmospheric circulation in the westerly-type EHT events is that there is a stronger polar vortex than normal and a shallow ridge moving eastward along the westerlies.Under the guidance of westerly wind,when the anticyclone anomaly controls over Northeast China,an EHT event is formed.When the blocking-type EHT event occurs,its corresponding atmospheric circulation shows that the blocking high over the Ural Mountain is stronger,and the northwest airflow subsides and heats Northeast China locating in the front of the high ridge,thus leading to the extreme high temperature event in Northeast China.The main circulation characteristics of wave-train-type EHT events are “+-+” wave-train-type circulation anomalies over Eurasia in the troposphere,and Northeast China is controlled by an anticyclone anomaly,resulting in an EHT event.Due to the maintenance of upstream wave energy,the duration,influence range and intensity of the wave-train-type EHT events are greater than those of the first two types.Based on the composites of SST anomalies 10—20 days before the occurrence of three types of EHT events,it is found that there are no significant SST anomalies in the North Atlantic before the occurrence of westerly-type and blocking-type EHT events.Before the occurrence of the wave-train-type EHT event,significant positive SST anomalies in the tropical North Atlantic are observed.There is a significant positive correlation between the SST anomalies in the North Atlantic and the intensity of the wave-train-type EHT event.Results of regression analysis show that the positive SST anomalies in the North Atlantic are conducive to the maintenance of zonal wave-train-type circulation anomaly over Eurasia in summer,which provides favorable conditions for the occurrence of wave-train-type EHT events.