Geotectonic researchers commonly hold that the Lower Yangtze area belongs to a stable craton while the South China area falls into an active orogen, whose basements are obviously different from each other. Based on an analysis of geological-geophysical data and the 1∶500 000 united compilation of aeromagnetic data, the authors made a comparison between the PreSinian basements of these two areas and revealed that they have similar Lower Proterozoic crystalline basements. This study gives a solution to the controversy as to whether there exist Cathaysia and a rigid basement in Lower Yangtze area or not.