Based on drilling cores and logging data, the sedimentary facies and its evolution characteristics of Chang 2 oil-bearing member in Yanchi-Dingbian area, Ordos Basin are studied. The result shows that fluvial system developed in Chang 2 depositional stage in this region. During the depositional period, there is a systematic change in channel types from meandering stream to anastomosing river. The meandering stream deposition developed at the bottom and middle sections （Chang 23, Chang 22） ofChang 2 member with thicker superposed channel sand body, higher sand-stone/ stratum ration, less floodplain and more channel deposits. While the anastomosing river deposition developed at the top section （Chang 21） of Chang 2 member with thinner channel sandstone-body, lower sandstone/stratum ration, less channel and more floodplain, swamp deposits. On the basis of sedimentary units division and correlation, the microfacies plane distributions of the 4 units are analyzed.