The complex lithology of Mesozoic buried-hill reservoirs in the Chengdao-Zhuanghai area of the Jiyang Depression, Bohai Bay Basin has been studied in this paper. The petrological characteristics, pore space, and reservoir quality of these rocks have been analyzed. Controlling factors of reservoir quality are also discussed. The result shows that the reservoir lithology in the study area includes igneous rocks and clastic rocks. The igneous rocks are dominated by andesite and volcanic breccia with limited distribution; clastic rocks are formed in braided river delta facies from which the advantage reservoir develops in the study area. Secondary dissolution pores are the main reservoir space. The remaining primary pores are mainly discovered in andesite, while the fractures are often filled by calcite. The reservoir in the study area has strong heterogeneity, and the sample porosity and permeability have a large distribution range. Reservoir quality is controlled by many factors. Fundamentally, the initial porosity of samples from different lithology-lithofacies or sedimentary facies is significantly different. Those with higher initial porosity also show a better performance in current porosity comparations. For the same type of rock, the difference in diagenesis is the decisive factor, compaction and carbonate cementation are the main pore-reducing effects of the reservoirs in the study area.