The AIP (air injection process) could be a promising technique to develop shale oil reservoirs because air has immense availability and free resources. The main differences between the AIP and conventional gas injection techniques are attributed to the complicated reactions among air, crude oil, and rock. The catalytic effect of the clay minerals on crude oil thermal-oxidative characteristics has been extensively studied; however, the confinement effect has rarely been discussed. In this study, the confinement effect of nanoscale porous media on crude oil thermal-oxidative characteristics was investigated using TGA (thermogravimetric analyzer) and DSC (differential scanning calorimetry) experiments, where the confinement environment was provided by the CPGs (controlled pore glasses). CPGs with three different pore sizes of 51, 85, and 172 nm were used. Also, the Arrhenius method was applied to investigate the crude oil oxidation kinetics during the AIP. The experimental results show that the confinement effect will not only inhibit the distillation endothermic process, but also increase the LTO (low temperature oxidation) exothermicity. Also, the confinement effect will lead to a better fuel deposition, hence increasing the HTO (high temperature oxidation) reaction intensity. It was also observed that smaller pore sized CPGs will result in a lower HTO exothermic peak temperature, which could benefit the AIP recovery performance if the HTO stage can be achieved. In addition, the activation energy values and the frequency factor values of the crude oil in both LTO and HTO stages were decreased under the confinement environment. This study can bring insights to researchers on the crude oil oxidation mechanisms under a confinement environment and help researchers to evaluate the feasibility of AIP in shale oil reservoirs.