A lot of isolated carbonate platforms occurred in the Late Palaeozoic Youjiang basin, Guangxi—Guizhou. Carbonate neptunian dike and synsedimentary normal faults occurred commonly on their margins. Paleoearthquakes are recorded by synsedimentary normal faults. On the margin of the leye platform, Guangxi, Late Devonian carbonate neptunian dike are discovered in the ooid grainstones and algal bindstones of the Upper Devonian Rongxian Fm. Those dikes are: agate laminated limestone dike, dolomite dike, microcrystal limestone dike, and algal bindstone dike etc. Early Carboniferous crinoidal grainstone dikes are also discovered there. Synsedimentary normal faults and their breccia and in situ earthquake shatter breccia are developed there, too. Thus provide new evidences for how the carbonate neptunian dike formed. In the Leye platform margin, there are at least two times normal fault moving: once occurred in Late Devonian and resulted in Late Devonian carbonate neptunian dikes in Late Devonian surrounding rocks; another occurred in Early Carboniferous and resulted in Carboniferous carbonate neptunian dikes and fault breccia in Late Devonian surrounding rocks. All the observations suggest that the synsedimentary normal faults on the Leye platform margin move and result in earthquake and carbonate neptunian dikes,based on the intense structure background. Such structure－deposit process records the stretch history of the Youjiang basin in late Palaeozoic.