The Chenxian-Huaiji structural belt trends NNE, crossing the Guangdong-Hunan border. The history of its development and deformation dates back as early as middle Devonian, ending in the Indo-Chinesian period and integrating the Cathaysian characteristics (Caledonian) with those of the neocathaysian (Yenshan). This belt represents, both in structural form and in evolution, the major traces belonging to the cathaysian system that prevails in SB China.With regard to the subdivision of the Cathaysian system, emphasis in the past has been put on the trend direction and recent activities, rather than on the tectonic processes and genesis. This easily leads to discrepancies and formalism.The present paper examines the Cathaysian system as a whole in terms of genetic processes, regional background, structural correlation, as well as the classification of structural forms in different orders. It comes to the conclusion that the whole system may be divided into 3 types, namely, the palaeo-, the median and the neo-Cathaysian and that the Chenxian-Huaiji structural belt belongs to the median type.The localization and spatial development of the Cathaysian system reflect a successive diversion and migration, which is incompatible with the polycyclic theory.The discrimination and determination of the trendings of the Cathaysian system may contribute to the understanding of the evolution in space and time of the region concerned. It helps comprehend the palaeogeographic landscapes, appreciate the ma-gmatic and volcanic activities, prospect the ore bodies, and, after all, provide an important basis for investigating the tectonic problems.