Abstract: Shale permeability is very important for exploration and utilization， and the micro pore structure is the main factor affecting shale permeability.In this paper， the TOC content and mineral composition of the shale of Longmaxi Formation and Niutitang Formation were determined.High-pressure mercury injection experiment and low-temperature nitrogen adsorption experimentwere carried out.The pore distribution and permeability of shale were measured.The effect of geological parameters and pore structure on shale permeability was studied.The study results show that: ① The number of organic pores increases with the increasing of TOC content in the shale sample， thus the porosity increases.The permeability of shale increases with the increase of clay mineral content. The pores in brittle minerals are poorly developed and negatively correlated with permeability and porosity. ② Ink bottle-shaped pore structure are distributed in the shale samples of Longmaxi Formation and Niutitang Formation. The pore throat is narrow and the interpore connectivity is poor. The pore size of the two groups of shales is between 4 nm and 40 nm， and the mesopores is the main channel for fluid occurrence and migration.③ The shale samples of Longmaxi Formation have a single peak distribution at a pore size of about 4 nm， and the shale samples of Niutitang Formation have a bimodal distribution at a pore size of about 4 nm and 7 nm.Relative to pore surface area and pore volume， pore morphology and connectivity have a more important effect on shale permeability.

Key words: gas shale, pore structure, geological parameters, permeability