Abstract: The Paleogene reservoir diagenesis of well A in Shwebo Basin is studied. It is during the middle diagenetic A1 and A2 stages, which is good for secondary porosity. Paleogene reservoir diagenesis evolution is special in research block:the first cementation was silicon cement happened before or simultaneously with the compaction. The second cementation was calcite cement and happened after the main compaction and porosity decreased by 15%. Thin section microscopy research shows that the two cementation reduced porosity by 4%~6%. Hypergenesis and the related tectonic squeezing movement are the controlling factors to the forming of Oligocene reservoir secondary porosity. New well of CNOOC in 2009 is located in pop-up and the lateral structure compression would influence deep layer sandstone diagenesis and porosity, but structural uplift to the upper reservoir would reduce the compaction. Special diagenetic evolution sequences and multiphase tectonic activities control the Paleogene reservoir quality. Deep research on the reservoir diversity and the mechanism of secondary porosity are important to the exploration in Myanmar.