Abstract: On the basis of core observation,identification of thin casting section,scanning electron microscopy and physical test and analysis,it is found that the reservoir rocks in Changxing Formation are mainly composed of grain dolostones, bioclast dolostone and reef dolomite.Types of the reservoir space are mainly the intracrystalline pore,the intercrystalline denudation pore,the dissolved pores in grains and the fractures.And the throat types are mainly slice-shape,pore-shrinking and the contracted neck throat.The reservoirs were mainly developed in the reef cap of the western part of the studied area and the shoal in upper Changxing Formation of the eastern part,dominated by sedimentary facies,corrosion and dolomitization.