With proven reserves of over 100 billion cubic meters, gas column height of over 1000 m and buried depth of over 4000 m, the Bozhong 19- 6 gas field is the largest deep- buried condensate gas field recently discovered in the Bohai Bay Basin that has a large but heterogenous reservoir. Based on the 3D seismic, drilling, well logging and thin section data, the characteristics of the buried rock reservoir are clarified, and the main controlling factors in the formation of high- quality reservoir are discussed. The results show that the bedrock reservoirs are mainly composed of metamorphic granite, and the storage space is mainly in structural fractures, while the dissolved pores along fractures and the crushed inter- granular holes are developed as well, resulting in an average porosity of 5% and an average permeability of 6. 48×10 -3 μm 2. Lithology, tectonic activity, and weathering jointly control the formation of large- scale reservoirs. Our results show that: ① 90% of the rocks in the study area are metamorphic granites with a high content of feldspar minerals and high brittleness, which provides the material basis for the formation of fractures; ② The intense compression during Indosinian period provides external power for the formation of large- scale fractures, which is the most critical factor in the development of large- scale reservoirs. The heterogeneity of reservoir plane distribution is a response to the different degree of fracture development in different structural locations; ③ Long- term weathering has further improved the reservoir properties within 300 m of the upper part of the buried hill, which controls the vertical heterogeneity of the buried hill. Those insights have important reference significance for the future exploration of bedrock buried hill in rifting basins.