A series of large- to- moderate earthquakes shocked, during the last decade, the southern region of the Sichuan basin in the conjunction area of Sichuan,Yunnan and Guizhou Provinces, which has provoked a vivid discussion on their seismogenic regime and seismic risk assessments in a cratonic block setting. In this study, we compiled regional active faults and historic earthquake epicenters and delineated four seismic sub zones, namely the Mabian- Yongshan, Ludian, Changning, and Zigong- Rongchang ones. An integration of seismotectonic data such as main shock- after shock distribution pattern, focal mechanisms and focal depth, shows that there exist two kinds of seismogenic structures: the basement strike- slip or reverse strike- slip faulting that dominated the seismic activity in the Mabian- Yongshan, Ludian and Changning sub- zones, and shallow reverse faulting that prevailed in the Zigong- Rongchang sub- zone. The maximum horizontal stress axe (compressional) orient from WSW- ENE to WNW- ESE. Double- earthquakes occurred frequently, with one shock event often triggering a conjugate strike- slip fault. These characteristics imply that the seismogenic structures of this seismic zone differ either from the reverse dominated faulting along the Longmen Shan seismic zone of the western Sichuan basin, or from the reverse to strike- slip- dominated faulting along the Xianshuihe- Anninghe- Xiaojiang seismic zone. It is considered that this is a neo- forming seismic zone in the interior of the Yangtze cratonic block. Tectonic stresses generated by eastward push of the Tibetan Plateau are transferring, via “Daliang Shan block”, to the south Sichuan basin, which activated the preexisting faults in the cratonic basement, and subsequently led to strike- slip to reverse strike- slip faulting earthquake sequences.