Diffusion and seepage of shale gas are very important geological functions in the process of shale gas enrichment. Under formation conditions, shale gas is transported in the micronano pore network in the form of diffusion and seepage. This paper takes the shale gas reservoir of the Longmaxi Formation in the Jiaoshiba area of the Sichuan basin as the research object. Based on the Knudsen number and gas adsorption mechanism, the main types of shale gas diffusion and seepage are clarified. The critical conditions of different shale gas diffusion and seepage types on the profile were established, and based on the basic physical definitions of Darcys formula and Ficks formula, the relationship between diffusion coefficient and permeability was established. The pore volume weight is used to identify the distribution characteristics of shale fullpore apparent permeability. Studies have shown that shale gas mainly has three types of diffusion and two forms of seepage in the ground, including surface diffusion of adsorbed gas, Knudsen diffusion, Fick diffusion, slippage and Darcy seepage, of whichthere are currently five types in the Jiaoshiba area. The critical pore sizes of diffusion and seepage types are 1. 2 nm, 1. 6 nm, 25. 0 nm, and 225. 0 nm, respectively, and the proportion of pore volumes corresponding to different diffusion and seepage forms is 15. 3%, 5. 6%, 60. 7%, 6. 4%, and 12. 0%. Macropores mainly provides gas percolation space, micropores and mesopores mainly provide gas diffusion space, and the percolation transport capacity is about 106 times that of the diffusion transport capacity.