Abstract: Applications of real sandstone micro-models to research micro-flow characteristics of Chang 6 reservoir in Jiyuan area of Ordos Basin, and analyzes the relationship between physical property, Pore throat and displacement efficiency by combining thin casting sections, scanning-electron micro-scopes and constant-rate mercury injection. Results show that there are finger-like, reticular and homogeneous flows in Chang 6reservoir research areas and the rock of the research area can be divided to remind intergranular pore dissolved pore as well as dissolve-remind intergranular pore. Different types of rock have different microflow characteristics in which displacement efficiency is different. The displacement efficiency of dissolve mind intergranular pore is high, and the dissolved pore is low. Heterogeneity is the main internal factors affecting displacement efficiency, and physical properties and pore throat impact on displacement efficiency weakness. Of the external factors, water injection pressure and injection water multiple have a large influence on displacement efficiency compared to multiple injections. Improvements to the water injection pressure will have a better effect on improving oil displacement efficiency.