Carbon isotopic composition of marine carbonates is a record for various important geological events in the process of earth development and evolution. The carbonates of Carboniferous,Permian and Triassic,as the transition from Paleozoic to Mesozoic-Cenozoic have very high delta~(13)C value. Taking this as the main point,and combined with the oxygen,strontium isotopic composition in carbonates,distribution of carbonate basin area through geologic time,the correlation of carbon isotopic composition of marine carbonates to sea level change,organic carbon burial flux,exchange of CO_2 content in atmosphere and ocean,and long cycle evolution of the earth ecosystems were approached. The results are shown as follows: ①The interval of delta~(13)C > 3 during Phanerozoic was concentrated in Carboniferous,Permian and the beginning of Triassic,but the beginning of Triassic was characterized by higher frequency and larger fluctuations in delta~(13)C value during a short time,whereas the Carboniferous-Permian presented a continuously stable high delta~(13)C value,indicating a larger amount of organic carbon accumulation in this time interval. Relatively high delta~(18)O values during this time was also observed,showing a long time of glaciations and cold climate,which suggest a connection among rapid organic carbon burial,cold climate,as well as pCO_2 and pO_2 states of atmosphere. ②The over consumption of atmosphere CO_2 by green plants during the time with high delta~(13)C of seawater forced CO_2 being transferred from ocean to atmosphere for the balance,but the decrease in the seawater amount and water column pressure caused by the global cooling could weaken dissolution capacity of CO_2 in seawater and carbon storage of marine carbonates,and also reduce the carbonate sedimentary rate and decrease the carbonate basin area globally from Devonian to Carboniferous and Permian. During the middle-late Permian carbonate was widely replaced by siliceous sediments even though in shallow carbonate platform,which resulted in the decrease of marine invertebrates,suggesting the Permian chert event should be global. ③The Phanerozoic ~(87)Sr /~(86)Sr trend of seawater showed a sharp fall in Permian and drop to a minimum at the end of the Permian,indicting input of strontium from the submarine hydrothermal systems ( mantle flux) . Such process should accompany with a supplement of CO_2 from deep earth to atmosphere and ocean system,but the process associated with widespread volcanism and rises of earth's surface temperature pricked up the mass extinction during the time of end Permian. ④Cold climate and increase of continental icecap volume,the amalgamation of northern Africa and Laurentia continentals were the main reasons responsible for the sea level drop,but the water consumption result from the significantly increased accumulation of organic carbon should also be one of the reasons for the sea level drop on the order of tens of meters. ⑤The mass extinction at the end Permian was an inevitable event in the process of earth system adjustment. It was difficult for marine invertebrates to survive because of the continuously rapid burial of organic carbon,and of the decrease of sea water amount and its dissolution ability to CO_2 . At last,at the end of Paleozoic,the supplement of CO_2 to atmosphere and ocean by widely magma activities resulted in a high temperature of earth surface and intensified mass extinction.