Objectives:There are any studies on volcanic ash in platform facies of Paleozoic scarcely, so as to hinder further study of tectonic evolution. Methods: line investigation, microstructure and element geochemistry Results: we found that volcanic ashes exists in the silty mudstone of Tangjiaba Formation of upper Cambrian, and the bauxite series of Du 'an Formation of lower Carboniferous Series, and the aluminium-bearing rock series of lower upper Permian series and superimposed clastic rocks, all of volcanic ashes developed resorption and devitrified structures.The volcanic ashes of upper Cambriancan display fine quartz porphyry, feldspar baby-crystal, spherules and white glass that represent distant rhyolite volcanic ash. Plagioclase and pyroxene are the main phenocrysts in the Lower Carboniferous volcanic ash, adding yellowish brown glass, whereas the geochemical characteristics of the zircon and the the rock elements show that they are alkaline basalts, and the detritus present that the ashes come from the near basaltic volcano. The volcanic ashes in the lower upper Permian are distributed in the terrestrial aluminite rocks and the overlying transgressive clastic rocks, and the volcanic ashes in the aluminite rocks are mainly basalt-Andesitic, whereas the ones in the clastic rocks of the roof are mainly rhyolitic, and the ones in the limestone below the P/T boundary are mainly rhyolitic, and the assembly of basaltic, Andesitic to rhyolitic, just means that it derived from the island arc which was inferred adjacent by the existence of detritus. Conclusions: By volcanic ashes it can be concluded that western Guangxi was of passive continental margin of the northern part of the Indian Plate in late Cambrian, and the acid volcanic ashes come from the arc volcano of the Indo-Australian Kuungan suture, and when it came to early Carboniferous period the west Guangxi was located within the Youjiang rift basin lying southwest margin of the Yangtze plate and volcanic ashes come from the regional volcanic eruption, and in the late Permian, the western Guangxi developed into back-arc basin and accepted volcanic ashes from the Paleotethyan island arc.