Chang-9 subsection of the Yanchang Formation is a new oil-bearing formation discovered in the Ordos basin. So far, the mechanism of oil migration and accumulation in the Chang-9 oil-bearing formation, especially oil migration, is still unknown. Resolving of this problem can perfect the theory of oil pool-forming in the Mesozoic Yanchang Formation in the Ordos Basin, and will play an important role in guiding oil exploitation and development. This paper focused on characters of source, transport system, migration pathway and power (so on) of oil in Chang-9 oil-bearing formation, and their differences in different areas. The results show that crude oil of the Chang-9 oil-bearing formation originated mostly from the Chang-7 subsection of the Yanchang Formation, with oil in the Zhidan region partially from Chang-7 and Chang-9 subsections. The Chang-9 crude oil migrates from upper to down. Pores in sandstone, structural fissures, and faults are dominant channels to transport crude oil. Overpressure zone commonly exists in the Chang-7 subsection of the Yanchang Formation and an apparent difference of fluid pressures between Chang-7 and Chang-9 subsections was also observed. Therefore, oil generated in the Chang-7 subsection can migrate downward driven by residual pressure in the overpressure zone, and charge in the Chang-9 sandstone reservoir with better physical property. This paper proposed three models of oil transport and accumulation for the Chang-9 oil formation and also discussed their mechnisams.