There is biggish difference in the reservoir distribution between the east and west ofYanchang Formation in Yishan Slope, Ordos Basin. In the eastern Zhijing- Ansai area, the reservoir mainly vertically distributed in Chang 6 Formation, and large area distribution in plane, while in the western Jiyuan area, multiple zones overlay in vertical and multiple rich zones developed in horizon in the same block. The analysis result shows that different migration and accumulation model cause the different reservoir distribution, which mainly displays in the following four aspects:①Different sedimentary scale. It is the main body of Shanbei multiple delta in the eastern Zhijing- Ansai area, which is large than that in the western Jiyuan area. ②Different reservoir property under the dual control of deposition and diagenesis. The reservoir property in Zhijing- Ansai area is better than that in Jiyuan area. ③Different migration pathway. The main migration pathway in Zhijing- Ansai area is connected sand body, while it is micro- fracture in Jiyuan area. ④Different migration and accumulation model. It is connected sand body and parallel migration in the eastern Zhijing- Ansai area, while it is fracture and vertical multi- points migration in the western Jiyuan area. The reservoir difference between the east and west of Yishan Slope is defined and the migration and accumulation rule is summed up, which provides significant guidance for exploration and deployment.