The Ordovician carbonate buried-hill in the southwest of Nanpu sag has been characterized by strong heterogeneity and complex control factors of karst reservoirs.In this paper, the research is carried out for the characteristics of buried-hill reservoirs by using core, imaging logging, thin section and seismic data.Through research, it is considered that the buried-hill reservoir are not typical weathering crust typeand are controlled by faults and lithology.The lithology of buried-hill reservoir is mainly composed of micrite-aplite dolomite with poor matrix porosity and small fractures in the reservoir space.Based on the analysis of regional tectonic activity, the formation of fracture system is mainly influenced by two tectonic movements of Neogene and Paleogene.On the one hand, tectonic movements create a large number of fault systems,but on the other hand, the faults connect the surface water to filling the reservoir space.At the same time, combined with core and thin section data, the development degree of fractures in the study area is also closely related to lithology.The density and opening degree of fractures in the powder-aplite dolomite layer is higher than micrite dolomite layer.After filling transformation, unfilled or semi-filled fractures and voids along the fracture dissolution are still visible.The results designate potential for further exploration and development in the research area.