Mud shale material composition is variable and its pore structure is complex，thus，clarifying the characteristics，the influence factors and the evolution of nano-pores in shale is of great significance to predict the oil/gas enrichment intervals. Shale from Well S in Dongying Sag was studied with the combination of N2 adsorption and mercury intrusion methods，to obtain the pore size distribution，the volume of different type of pore，and other quantitative parameters. The results show that the argillaceous siltstone is dominated of macropore，and the silty mudstone and mudstone are mainly characterized by mesopore and micropore. By analysing the relationships among mineral composition，organic composition and pore structure，it is found that clay content and clay mineral type in mud shale have the most strong effect on micropore and mesopore.And the influence of carbonate minerals on the pore structure is controlled by its genesis. Furthermore，the total organic carbon（TOC），and organic matter type affect more strongly the pore structure of mud shale. By analyzing the evolution characteristics of pore structure，mineral composition and organic composition，it is found that mineral transformation，hydrocarbon generation of organic matter and burial compaction together lead to the multiple stages pore evolution during burial evolution.