Changxing Formation reef-beach reservoir features are studied with core, thin section observation and logging explanation. It turns out that the main reservoir rocks are reef dolomites and reef limestone, and the reservoir space is mainly secondary pore with poor reservoir property. The reservoir types are mostly fracture-pore and pore-fracture with low-porosity and low-permeability. Moreover, dolomitization and solution promoted the property of reservoir and provided advantages for the formation of secondary pores.