Based on the data from the monthly Sea Surface Temperature(SST) data of Hadley Center, NCEP/NCAR reanalysis data and the observed temperature data of 160 stations in China during 1951—2016, the association and possible mechanism between the North Atlantic SST tripole in summer and interannual temperature variability in China are investigated. The summer North Atlantic SST tripolar anomaly is significantly negatively correlated with the interannual temperature variability in the Southwest of China during the same period. The summer North Atlantic SST "-+ -" tripolar anomaly stimulates the northern hemisphere mid-high latitude Eurasian teleconnection wave train, which causes the potential height of the Baikal region to increase, resulting in an anticyclonic circulation anomaly; the East Asia region to decreased, resulting in a cyclonic circulation anomaly. The Southwest region of China in the middle and lower troposphere is located in the East of the Baikal anticyclonic circulation and the West of the East Asian cyclonic circulation. Under the joint action of the two, it is affected by the anomalous northerly airflow, which is conducive to the southward and accumulation of cold air. In the same time, the East Asian subtropical westerly jet in the upper troposphere is southward and the Southwest region of China is located in the anomalous updraft on the south side of the jet stream, this configuration will cause the temperature in the area to decrease; vice versa.