【Purposes】 In China, the exploration and development of deep oil and gas resources have gained significant attention in recent years. In order to meet the demands of development, many scholars have conducted research on the process of deep natural gas diffusion and have made noteworthy advancements. 【Methods】 Aimg to evaluate the applicability of deep natural gas diffusion behavior and the carbon isotope fractionation effect, the study is based on an analysis of Fick diffusion, Knudsen diffusion, surface diffusion, and configuration diffusion. Establishing an accurate mathematical model is believed crucial in comprehensively understanding the mechanism of diffusion behavior. 【Conclusions】 The current models for coupling can analyze not only the behavior of natural gas diffusion in deep nanometer pores, but also how it affects the overall intensity of diffusion and the degree of carbon isotope fractionation in low-permeability conditions. Furthermore, these mathematical models allow for the calculation of gas loss intensity when combined with the history of strata evolution. The objective of this research is to provide a more precise and quantitative representation of deep gas diffusion behavior. This will aid in the exploration and development of deep oil and gas reserves, and also have significant implications for the evaluation of deep gas reservoirs in terms of preservation and destruction.