Abstract: Through the regressional calculation and simulation on the δ¹⁸O of micritic limestone and R_max^o of associated argillous asphaltum from the 11 Ordovician sections in the YangtzeArea,it is suggested that the oxygen isotopic exchanges of the micritic limestones shouldbe dominated by buried paleo-geotemperature, Based on the above analysis,the author ofthis paper discusses on the oxygen and carbon isotopic characteristics of the 6 kinds of diageneses with different diagenetic environments in the Ordovician carbonate rocks of the 6section points of the Yangtze carbonate platform. Furthermore,the author suggests thegeological significance of the discussions in the assessment on the maturity of organic matter and oil/gas accumulation, preservation,and migration.