Stable isotopic method can be used effectively in the diagenetic research of deep water carbonate rocks.According to the oxygen and carbon isotopic compositions of the Early Palaeozoic deep water carbonate rocks developed along the southeastern marginal slop of the Middle Yangtze carbonate platform

some diagenetic environments and diagenetic mechanisms are as fallowe:1)the δ

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O values of nodules of Lower Ordovician nodular limestone are always more positive than those of matrix

suggesting that the prototype of the modular limestone was the product of solution and cementation occurred repeatedly on the sea floor;2)the Lower Cambrian massive dolomite with relatively concentric values of δ

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O and δ

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C was the product of high density brine replaced dolomitizatin

whereas the lower Ordovician massive dolomite with high negative δ

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O value was formed by the deep burial dolomitization;3)Burial recrystallization altered strongly the Lower Ordovician carbonate rocks

and made them to have the same high negative δ

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O values.