Gulong shale oil is a terrestrial pure shale type shale oil reservoir characterized by low rock porosity and permeability, developed nano pores and shale fractures. However, large-scale fracturing development encounters challenges such as rapid energy attenuation and production decline in the formation. Therefore, it is imperative to conduct feasibility studies on enhancing formation energy supplementation and improving recovery technology. Based on the characteristics of the Gulong shale reservoir, CO2 injection molecular simulation, indoor evaluation experiments, and parameter optimization design research were carried out. Molecular simulation was employed to evaluate the influence of CO2 on different types of pore adsorption layers' thicknesses. Indoor CO2 injection experiments were performed to assess the expansion capacity and miscibility pressure of CO2 when in contact with crude oil. Furthermore, numerical simulation methods were utilized for designing and optimizing various parameters for CO2 injection. The results demonstrate that CO2 exhibits a strong displacement ability towards the pore boundary layer while possessing a high coefficient of expansion and a low mixing pressure under original formation conditions, thus achieving effective mixing effects Numerical simulation design optimizes the injection rate of 200 t/d for a single well, with an optimal shut in time of 30 days and an optimal soaking cycle of 5 rounds. Shale oil gas injection can effectively replenish energy reserves and oil increase effects, it is expected that a single well will accumulate 4523 tons of oil through this approach. The research findings have important implications for formulation gas injection development plans specifically tailored for Gulong shale oil operations while providing robust technical support for efficient development.