The South China plate,convert from passive continentaation-Longmaxi Formation black shale.In order to exploring the formation background of the black shal margin basin to foreland basin in Ordovician-Silurian,and deposits widely distributed Wufeng Formle,sedimentary sequence and geochemical study were carried for well Daoye-1 as an example in this study.Results show that the Wufeng Formation and the bottom of the Longmaxi Formation mainly consist of siliceous carbonaceous shale and bentonite,with the U/Th is 0.2~2.90,the V/Cr is 1.18~14.34,the Ni/Co is 2.31~11.59,and the TOC is 0.68%~5.91%.The REE patterns curve is flat.The δEu showed weak positive anomalies and individual weak negative anomalies.The upper part of Longmaxi Formation and Xintan Formation mainly consist of mudstone and calcareous mudstone,with the U/Th is 0.16~0.23,the V/Cr is 0.88~1.79,the Ni/Co is 1.77~3.91,the TOC is 0.1%~0.84%.The δEu showed obviously negative anomaly,and the REE patterns curve is right type.Such features indicate that the Wufeng Formation and the bottom of the Longmaxi Formation formed in the reductive environment with intermittent hypoxia,the upper part of Longmaxi Formation and Xintan Formation mainly formed in the oxygen-enriched environment.According to the comprehensive analysis based on the distribution characteristics of bentonite,which indicated that the Wufeng Formation and the bottom of the Longmaxi Formation shale formed at the early period of the foreland basin in convergence background,strong volcanism brings nutrients to the Mainland marginal sea,stimulates the increase of primary production,and causes rapid hypoxia in deep water,which may be the main cause of hypoxia in the bottom of the ocean during the same period.