Abstract: In view of the development problem of complex lithology diamictite in the lower third section of Paleogene Shahejie Formation in KL16 structure of Laizhou Bay Sag in Bohai Sea, the characteristics of diamictite reservoir were studied by using well logging, logging, drilling and 3D seismic data, combined with constant velocity mercury injection, casting thin section, scanning electron microscope, rock and mineral analysis and DST test data, and 8 cores were selected to carry out acidization experiment. The results show that the reservoirs in the lower third section of Shahejie Formation are mainly thin interbeds, with a single layer thickness of 0.8～5.0 m. The lithology is extremely complex, mainly sandstone, dolomitic limestone, argillaceous dolomite, dolomite, calcareous sandstone and tuffaceous sandstone. After acidization, feldspar and carbonate minerals are dissolved, and the porosity of tuffaceous sandstone and diamictite is improved. The effect of diamictite reservoir reconstruction is the most obvious, and the permeability is increased by (46.0～77.5)×10⁻³ μm². The permeability of sandstone reservoir changes little, and the permeability is increased by 34.1×10⁻³ μm². The tuffaceous sandstone reservoir has a velocity-sensitive reaction, and the permeability is reduced by 9.1×10⁻³ μm².The research results provide a reliable basis for guiding the optimization of KL16 structural stimulation measures, productivity evaluation and production prediction, and also have great reference significance for the development scheme compilation and development production practice of other similar oilfields in Bohai Bay Basin.