The hydrocarbon source rock in Upper Ordovician-Lower Silurian strata is one of the four kinds of regional marine source rocks in southern China, and the researches on the palaeo-environment for its formation and development constitute one of the basic problems concerning the marine hydrocarbon accumulation theories of southern China. Two typical sections were selected in this study, and a geochemical analysis of Upper Ordovician-Lower Silurian sedimentary rocks was conducted along these sections. Environment indicators were chosen to restore the palaeo-environment. The results show that the high-quality source rocks are concentrated in Upper Ordovician Wufeng Formation and at the bottom of Lower Silurian Longmaxi Formation. Such indicators as V/（V+Ni）, Ni/Co, Ceanom, δEu and δ13Corg have good relations with TOC in these format ions, suggesting that good quality hydrocarbon source rocks are developed in an anoxic environment. Geochemical indicators in the upper part of Longmaxi Formation show that the anoxic environment had been destroyed, which was accordant with the high-energy sedimentary environment at that time and was disadvantageous to the formation of hydrocarbon source rocks