The law of shale gas micro-migration in micropore and nanopore, and the law of adsorption and desorption are studied by majority researchers. Considering the porosity and the permeability of the shale, the size of fluid potential, which controls the transporting way of shale gas in the shale, is decided by the pore fluid pressure. According to the difference of the pore fluid pressure in different geologic environment, three theoretical models of the gas intra-layer migration mechanism have been set up: ①the intra-layer migration model of fold; ②the model of intra-layer migration caused by different denudation; ③the model of intra-layer migration caused by different degree of organic metamorphism. Micro-migration creates the necessary pathway for intra-layer migration, and intra-layer migration can advance the process of desorption and liberation. Furthermore, the study about the intra-layer migration mechanism of Jiaoshiba anticline in East Sichuan shows that the distribution of shale gas and pore fluid pressure conform to the intra-layer migration mechanism built in this passage. With the researching about the intra-layer migration and the micro-migration, seeking the advantageous exploring target could be easier.