Abstract: [Objective] In recent years, breakthroughs have been made in shale gas exploration in the Wulalike Formation on the western margin of the Ordos Basin, opening up a new field for Marine shale gas exploration in the North China Plate. Systematically characterizing the microscopic pore structure of low-TOC marine shale gas reservoirs and clarifying the main controlling factors of pore development is crucial for the prediction and evaluation of shale gas in the Wulalike Formation.[Methods]Well R16 was selected as the key research object, and a series of experimental tests such as X-ray diffraction whole-rock mineral analysis, argon ion polishing scanning electron microscope observation, and low-temperature gas adsorption were carried out. A detailed characterization of the shale gas storage space and capacity of the Wulalike Formation was conducted.[Results] The following results and conclusions were mainly formed: (1) The reservoir as a whole has low porosity and low permeability. The upper section is mainly composed of clay shale, the lower section is mainly composed of siliceous shale, while the middle section has interbedded development of clay shale and mixed shale The porosity of the upper section is the highest, followed by that of the middlesection, and the lowest in the lower section. Overall, organic pores do not develop, and inorganic pores and micro-cracks are predominant. (2) The pore volume of shale ranges from 4.021 to 8.307 cm³/kg, with an average of 6.031 cm³/kg. The main contributors are mesopores and macropores. The specific surface area ranged from 1.131 to 6.605 cm²/g, with an average of 2.986 cm²/g. The main contributors were micropores, followed by mesopores, and macropores were the least. The main occurrence space of shale gas is pores ranging from 0 to 10 nm, with an average proportion reaching 86.7%. A large number of micrometer-sized micro-fractures are connected with nano-sized pores, forming a complex pore-fracture network system, which is the main channel for seepage and diffusion of shale oil and gas. (3) The pore structure, physical properties and gas-bearing capacity of the reservoir are mainly influenced by clay minerals, which makes the pore volume and specific surface area of the upper and middle sections more developed than those of the lower section. Illite, as the main mineral, its intergranular pores provide a certain storage space for the reservoir and constitute the main carrier for the occurrence of natural gas.[Conclusion]Comprehensive analysis indicates that the siliceous shale in the lower member of the Wulalike Formation and the argillaceous-mixed shale interbedded interval in the middle member are favorable exploration intervals.[Significance] This study provides an in-depth analysis of the gas storage characteristics and influencing factors of low-TOC shale reservoirs in the research area, which will contribute to advancing the exploration of marine "low-TOC" shale gas in northern China.