The reservoir space and microscopic pore structure of Cambrian black shales in the Yichang area of western Hubei were studied through the analysis of low-temperature liquid nitrogen adsorption and scanning electron microscopy. Besides，the main control factors of pore development of shale were determined based on experiment data of total organic carbon and X-ray diffraction. The results indicate that the storage space type of shale gas reservoir in the Shuijingtuo Formation are mainly residual intergranular pore，secondary dissolution pore，mineral moldic pore，intercrystal pore，microcrack and organic pore. Micropores and small pores are the main pores in shale. For pores with a diameter less than 10 nm，the average contribution rate to specific surface area can reach 87.51%，and for pores with a diameter more than 10 nm，the average contribution rate to pore volume is 56.32%. The clay minerals can provide more adsorption sites and pore space for shale gas occurrence in the shale of the study area. Quartz are favorable for shale pore development and the pore structure will become complex due to the high content of carbonate minerals.