The thickness and sedimentary features of the Kuanyinchiao Member of Wufeng Formation and Longmaxi Formation in northeastern Chongqing vary greatly. Analysis of five profiles, Well YC1, Tianba profile (TBP), Bailu profile (BLP), Sifangdong profile (SFD) and Lianghekou profile (LHP) from west to east, shows that the Kuanyinchiao Member is dominated by grayish mediumthin bedded argillaceous limestone, locally containing shelly fauna (the Hirnantia fauna). It is common that argillaceous limestone is intensively weathered into brownishyellow. The Kuanyinchiao Member is characterized by grayishblack argillaceous limestone and hosting shelly fauna in LHP, and increasing content of silty or sandy grains apparently in SFP. The characteristics of organic carbon isotopic distribution in these profiles show many resemblances, and can be correlated regionally and even globally. The Kuanyinchiao Member of Hirnantian Stage shows positive δ13C org excursion with a roughly similar amplitude and peak value probably due to local environment perturbation. The δ13Corg value increases pulsatively from the Wufeng Formation to Kuanyinchiao Member, with a few peaks. On the contrary, δ13Corg shows continuous, steady fall from Guangyinqiao Member to the Longmaxi Formation, with drop rate depending on the thickness of the Longmaxi Formation.