Institute of Petroleum Geology，Petroleum Exploration & Production Research Institute，SINOPEC，Wuxi City，Jiangsu Province，214126，China；3.Guangzhou Institute of Geochemistry，Chinese Academy of Sciences，Guangzhou City，Guangdong Province，510640，China；） Nitrogen adsorption method and mercury injection experiment were applied to characterize the joint pore distribution，porosity and fractal characteristics of Permian shales in south Anhui Province，the Lower Yangtze region. The results illustrate that：the pores in the Permian shales are dominated by micropore and macropore，and the volume of micropore accounts for 33.63% to 81.08% of the total pore volume with an average of 56.45%；the joint porosity is significantly higher than the porosity obtained by mercury injection method with an average increase of 96.06%；both the micropore and transition pore to macropore could generate obvious fractal characters for the Permian shales，and the fractal dimensions of the micropores are more dispersed than those of the transition pores to macropores，which indicates that the degree of heterogeneity and complexity of the micropore are higher than that of the transition pore to macropore；the porosity and fractal dimension of the micropore have positive correlation with TOC，specific surface area and hydrocarbon generation potential but negative correlation with quartz content；while the porosity and fractal dimension of the transition pore to macropore have negative correlation with TOC and quartz content，and no correlations with clay mineral content and specific surface area. With the increase of buried depth，the porosity and fractal dimension have no obvious variations for the micropore，but a certain decrease for the transition pore to macropore. The fractal dimension is more sensitive than the porosity to the buried depth.