Based on the heat stress index, the daily mean temperature and relative humidity data of 1 814 weather stations over China from 1961 to 2016 and the NCEP／NCAR reanalysis data were used to analyze the interannual variability of heat stress and possible influencing factors in northern China. Results show that the interannual variation of extreme heat stress events in northern China experienced an interdecadal transition around 1990. Before 1990, the interannual variability of the frequency of extreme heat stress events was relatively small, and its interannual variation was mainly affected by the Eurasian teleconnection pattern, Antarctic Oscillation, and East Asia-Pacific teleconnection pattern. After 1990, the interannual variability of extreme heat stress frequency significantly increased and it was mainly affected by East Asia-Pacific teleconnection pattern.