Abstract: The Paleogene reservoirs in Lvda area of Liaodong Bay are characterized by feldspar sandstone and lithic feldspar sandstone. The lithoclasts include mainly magmatic rocks and some metamorphic rocks. The cementation type is dominated by pore cementation, with mainly secondary pore. The diagenesis of the sandstones involves compaction, cementation, dissolution and replacement, of which the cementation decreases the primary pores of reservoir rapidly, whereas the dissolution increase the secondary pores. Therefore, the diagenesis has obviously reformed the pore structure. The evolution of porosity is well correlated to the diagenetic stage.