Abstract: The present paper gives a detailed description of the dolostone reservoirs and their genesis in the Zaring oil pool in southern Qiangtang Basin on the basis of thin sections,cast sections,capillary pressure curves and cathodeluminescent images.The dolostones have experienced several types of postdepositional diagenetic modifications,of which dolomitization,dissolution,recrystallization and tectonic stress processes have exerted an important effect on porosity and permeability.The accommodation spaces include intercrystal pores and intercrystal solution openings.The well-developed rimmed textures indicate that the dolostones in the study area resulted from the diagenetic replacement of limestones by mixed meteoric-marine pore fluids.