Abstract: Along with the deep exploration of the Xihu Sag in East China Sea,the complexity of deep sweet reservoir distribution has become increasingly prominent.From organic matter evolution,clay dehydration and the conversion problem,the concept of coordinated diagenesis has been introduced in this paper.Through integrated analysis about organic matter and the clay evolution process in several major diagenetic events,the influence of organic acid,CO₂,and hydrocarbons generated during thermal evolution process of organic matters on reservoir diagenetic environments has been analyzed.In addition,study has been conducted on clay dehydration,transformation and material exchange between the reservoir during the process of the epigenetic,trying to find the relationship from testing data of sandstones and mudstones and put forward some new ideas in order to deepen the analysis of reservoir diagenesis,and help to establish a reliable reservoir prediction model for deep reservoir study