It is suggested that reservoir spaces of Longmaxi shale gas reservoir in XX area of southern Si- chuan and northern Guizhou were diversified,by using of Scanning Electron Microscope (SEM), test data and adsorption/desorption isothermal that produced from Multipoint Brunauer Emmett Teller (MBET) to do research on the types of reservoir spaces and micro-pore structure characteristics of shale gas reservoir. Reservoir spaces mainly include residual primary intergranular pores, intercrystal pores, mineral moldic pores,secondary dissolution pores, micropores among clay minerals, organic matter pores, structural frac- tures, diagenetic shrink micro-fractures, interlayer lamellation fractures, overpressure breaking fractures and so on. We found out that the pore volume and specific surface area of Longmaxi mud shale is larger and has a good positive correlation,and thought that the more developed the micro-pores were,the bigger the mud shale have the pore volume and specific surface area. It is also beneficial for mud shale to adsorb shale gas. This study established pore models of mud shale,and analyzed micro-pore structure of Longmaxi For- mation mud shale. Using adsorption/desorption isothermal, this study also proposed Longmaxi Formation mud shale mainly developed micro-pores,and argued that in those micro-pores,flask (ink-bottle) shaped pores and open air permeability pores supplied the largest pore volume and specific surface area for mud shale. We thought that organic carbon content (TOC), the content of illite/smectite interstratified clay mineral and thermal evolution degree were the major factors to control micro-pores structure of Longmaxi Formation shale gas reservoir in XX area of southern Sichuan and northern Guizhou.