Abstract: Shale gas serves as a significant strategic successor resource for future oil and gas reserves and production in China. Thus, a profound understanding of the adsorption mechanism of shale gas in shale reservoirs is crucial to accurately predict and evaluate shale gas reserves. In this study, we utilized two simulation methods, molecular dynamics simulation and Giant Canonical Monte Carlo simulation to examine the adsorption characteristics of kerogen under varying temperature and pressure conditions. We compared the results under identical temperature and pressure conditions for different mineral–kerogen composite models. Moreover, we examined the effects of temperature, pressure, and mineral species on the kerogen adsorption mechanism. The results indicate that shale formations with high organic matter content and a substantial proportion of non-clay inorganic minerals, as well as those subjected to higher temperature and pressure conditions than the shallow layer, possess a greater capacity to accommodate shale gas. This study examined the adsorption mechanism of methane in shale gas using different mineral–kerogen composite models. The findings of this study provide more accurate guidance and support for efficient development of shale gas.