Evidences of microbial origin of organic matters of Niutitang shale gas reservoir were discussed from both micropaleontological
and organic geochemical perspectives. The environmental scanning electronic microscope-energy dispersive
spectrometry system（ESEM – XEDS）was applied to analyze the morphology and chemical compositions of microfossils；
in addition，the extracts of shale core were tested by using gas chromatography-mass spectrometry（GC – MS）method. Results
indicate that all the microbial fossils discovered in Niutitang shale are of high N and C content（more than 30%）and all the
fossils can be subdivided into three types，including concentric circularity shape，smooth coccoid shape and coccoid shape with
a surface crack. The extracts test results indicate that normal paraffin ranging from nC12 ∼ nC32 were detected，and is characterized
by light n-paraffin and even-carbon-number predominance（main peak is nC16）. In addition，some isoprenoid were also
detected from extracts e.g. pristine，phytane，and squalene. The discovery of microorganism fossils and organic geochemical
characteristics of shale cores provides strong evidences for flourishing of microorganism in Yangtze Shelf Sea during Sinian to
Early Cambrian period and the microbial origin of hydrocarbon source materials of Niutitang Formation.
