Seismic. geological, drilling and log data reveals that reef reservoir is developed in Changxing group of Yuanba area. Its seismic facies belts include open platform facies, platform margin reef flat facies, slope facies, deep sea facies. The result indicates that in the reef reservoir, the beneficial oil/gas-bearing area corresponds to the characteristics such as weak amplitude, low frequency, relatively large frequency attenuation gradient, low impedance and low velocity. Drilling data proved the beneficial area has good oil/gas-show, which demonstrates that the reservoir prediction method is available.