Shale gas has been successfully developed in the Wufeng- Longmaxi Formation in the Sichuan basin, China. However, due to the influence of shale gas preservation, shale gas enrichment varies significantly, which has challenged the optimization of shale gas exploration and development targets. Therefore, it is of great significance to study the mechanism and mode of marine shale gas preservation and to increase the shale gas production. In this paper, the Wufeng- Longmaxi Formation marine shales in the Sichuan basin were used to conduct an integrated procedure including basin modeling, fluid inclusion analysis, overburden porosity and permeability, triaxial rock mechanics tests. Major findings include: ① tectonic evolution controlled the micro- cracks, free gas enrichment and overpressure. Differing tectonic evolution processes and their intensity control the occurrence and shale gas contents. The late uplift and low tectonic intensity is favorable for shale gas preservation; ② the mechanism of top and bottom sealing is lithological and physical sealing. Tight lithology, thickness and pore structure of shales control the top and bottom sealing. The mechanism of self- sealing shale gas are the capillary and intermolecular forces, which are controlled by pore connectivity and methane adsorption; ③ based on burial depth and deformation evolution, the preservation models of marine shale gas in the upper part of anticline structure and the lower part of syncline structure have been established. Burial depth greater than fracture depth, and an angle greater than 120° are conducive to the anticline preservation of shale gas. The buried depth of permeability decrease and an angle less than 10° are conducive to the preservation of shale gas. This paper is of great significance for further exploration and development of marine shale gas in China.