Lithofacies and overpressure are the most important factors affecting the pore structure of the reservoir. However, the relative dominance of these factors remains debated, leading to variations in the characteristics and evolutionary models of pore structure during the uplift process of gas reservoirs. This study focuses on the shale of the Wufeng Formation- Longmaxi Formation in the Sichuan basin and its surrounding areas as the research subject. By analyzing mineral composition, organic geochemistry, field emission scanning electron microscopy, digital image processing and extraction, and full- aperture pore characterization (CO2, N2, and high- pressure mercury intrusion), the effects of lithofacies and overpressure on shale pore structure during the uplift process after reaching maximum burial depth were investigated. Additionally, an evolutionary model of shale pores during gas reservoir uplift was established. The results reveal the following: ① Organic- rich siliceous shale exhibits a larger pore- specific surface area, pore volume, and fractal dimension compared to organic- poor clay shale in the same pressure zone. ② Organic- rich siliceous shale in different pressure zones experienced a later uplift period and a smaller uplift range. It demonstrates a larger specific surface area, pore volume, roundness coefficient, and fractal dimension. Overpressure has a maintaining effect on pores, preventing compaction and minimizing deformation. ③ The influence of lithofacies on shale pore- specific surface is mainly observed in micropores, while overpressure predominantly affects pore volume in mesopores and macropores. Based on these findings, models of shale quartz compressive pore- preserving and reservoir overpressure pore- preserving during gas reservoir uplift were established. This study enhances the understanding of shale gas accumulation mechanisms and is of great significance for evaluating shale gas reservoir preservation and potential damage.