Reservoirs of ZaoⅡ and Zao Ⅲ of the first member of Kongdian Formation in Zaoyuan Oilfield are dominated by channel sands developed on alluvial fans. Three long-term base level cycles and 11 middle-term base level cycles are recognized in ZaoⅡ and ZaoⅢ reservoirs, and each middle-term cycle is composed of one to five short-term base level cycles. Short-term cycles can be divided into high and low accommodation space cycles which represent two kinds of channel sand bodies with ifferent characteristics. Middle-term cycles can be classified into symmetry and asymmetry types. Sediments at high accommodation stage of long-term cycle are mainly mud, with single channel inserted in. With the rise of the long-term base level, the ratio of width to thickness of sand bodies increases and sand content decreases.