Taking the shale of the Cambrian Qiongzhusi Formation of Southeastern Sichuan Basin as an example, a variety of technical methods including rock thin slice identification, mineral X ray diffraction, pressure mercury-adsorption joint determination, helium porosity measure, argon ion polishing-scanning electron microscope, and quantitative characterization of shale gas reservoir by logging are applied to analyze the types and structures of the shale of the Cambrian Qiongzhusi Formation, and to discuss the mechanism of organic-inorganic compound connected pore systems and the significance on shale gas enrichment. The results show that: (1) the pores in the organic shale are mainly micropores (< 2 nm) and mesopores (2~50 nm), followed by macropores (> 50 nm); (2) the pore types are mainly intergranular pores and clay mineral interlayer pores, mostly triangular, polygonal and slit, then are irregular organic pores in organic matter-clay complex; (3) the rich organic shale has favorable conditions for the development of organic-inorganic composite connected pore systems, which improves shale storage ability and controls the enrichment of shale gas.