Abstract: Chang 6 reservoir in Jiyuan area of Ordos Basin belongs to low porosity,low and ultra-low permeability.Based on SEM,cast sheet,X-diffraction and flooding experiments of real sandstone microscopic model,the study on diagenetic facies and micro seepage characteristics of Chang 6 reservoir was carried out.The results show there were significant differences of flow characteristics between different types of diagenetic facies.By using comprehensive analysis of experimental results of real sandstone microscopic model displacement,the chlorite cementation residual intergranular pores diagenetic facies is the most favorable diagenetic facies and feldspar dissolution followed.