Based on the study of carbon and oxygen stable isotopes of the related cements and rocks in the Late Permian reef of Hunan Province, and combining the observation of thin sections, electron-probe analysis, and enclave thermometry, the relative diagenetic characteristics of reef dia-genesis in the studied area are discussed. The authors consider that: (1) the C and O stable isotopes values of cements from the early to late stages in the Late Permian reef of Hunan Province tend to become smaller on the whole, suggesting that the reefs have a continuously buried diagenetic history; (2) the dolomitization seen in the reefs mainly results from burial compaction, and the reefs are not influenced by the early fresh or mixed water; (3) the calcite cements of the coarse-giant crystals were formed during the deep-buried period, but there are obvious differences in the degree of deep burial between the southern and the western Hunan reefs.