Barite concretions were found in siliceous rocks and mudstones in the lower Silurian Longmaxi Formation on the northern margin of the Yangtze block. Their mineral compositions are barite crystals, pyrite, clay or quartz. Based on an analysis of the macroscopic and microscopic morphology of barite and strontium isotopes, the authors hold that barite deposits precipitated from the enclosed pore water in sedimentary column. The high productivity and anoxic bottom water provided the environment for the formation of barite. Bio-barite could be formed by biological effect in the seawater. Afterwards, bio-barite was dissolved by sulfate bacteria (BSR) in the sulfate depleted zones. Sulfate in pore water was evolved from the penecontemporaneous seawater. The host mudstone indicates high preservation potential in an anoxic depositional environment. This study has provided some implications for the further understanding of the paleoenvironment of the northern margin of the Yangtze block in early Silurian.