The Late Paleozoic Yongan Basin is located in the southern margin of the Wuyi Mountains uplift of the Cathaysia block. δ13Corg data from the Yongan Basin and other basins in Southeas China are compared to illustrate the similarities and differences between different basins and between rocks of different ages.TOC values of the Yongan Basin are similar to those of equivalent sediments in Pingle Basin. These similarities indicate that the sedimentary environment of the Yongan Basin is similar to other basins in the region, representing a marine-terrestrial transitional environment. There are also differences in TOC contents among sediments of different ages. Most organic-rich sediments in the ZM (Zhejiang-Fujian coast) area are of Mesozoic-Cenozoic age.