The Shuangyang Formation reservoir of Paleogene is the important oil-gas abounding formation. Based on the lithological feature, diagenesis of Shuangyang Formation are revealed by thin section observation, Scanning El ectron Microscope observation, clay minerals X-diffraction analysis and other methods. It is revealed that there are compaction, cemetation, metasomatism and dissolution .It shows a typical feature that montmorillonite translate to illite of Shuangyang Formation reservoir, and it undergoes montmorillonite graduation zone, the first rapid translation zone and second rapid translation zone. Corresponding the diagenesic stage is divided into early diagenesic B stage , late digenesic A1 and diagenesic A2. stage 。The order of diagenesis of Shuangyang Formation is builted. The types and intensities are different in the vertical, which causes the reservoir property zonal.