Abstract: The southeastern part of the Sichuan-Yunnan fault block is located at the southeastern corner of the eastern Xizang-Sichuan-Yunnan fault block, a secondary tectonic unit on the eastern margin of the Qinghai-Tibet Plateau. It is intersected by the nearly north-south trending Xiaojiang fault zone on the eastern side and adjoins the South China block. At present, this region features intense tectonic activity and frequent strong earthquakes. An in-depth analysis of the current seismic activity characteristics in the southeastern Sichuan-Yunnan fault block is of great significance for assessing the seismic hazard of this region in the future. Combined with the regional tectonic setting, this paper analyzes the characteristics of historical strong earthquakes in the southeastern part of the Sichuan-Yunnan fault block, discusses the correlation of seismic activity between adjacent structures on the eastern and western sides of the southern segment of the Honghe fault zone, and obtains the following understandings: Historical strong earthquakes among different structures in the southeastern Sichuan-Yunnan fault block show a certain temporal correlation. The historical strong earthquakes in the southeastern Yunnan arcuate tectonic belt have experienced three active periods, during which strong earthquakes in adjacent structures triggered each other, and their spatial distribution is closely related to the distribution of fault zones. Historical strong earthquakes along the Qujiang fault and the Shiping-Jianshui fault zone have verified the rupture gap theory. By analyzing five earthquake cases in the southeastern Yunnan arcuate tectonic belt since 1965, it is found that seismicity clustering exists before some moderate-strong earthquakes. The adjacent structures on the eastern and western sides of the southern segment of the Honghe fault zone show a good correlation in seismic activity, which is conducive to the formation of seismic gaps. Through an analysis of geothermal anomalies on both sides of the Honghe fault zone before the 2022 Honghe M_s 5.0 earthquake, it is inferred that stress interaction may exist between the structures on the eastern and western sides of the southern segment of the Honghe fault zone.