As the world pays more attention to carbon reduction, it is of great significance to identify the factors of CO2 to achieve carbon peaking and carbon neutrality goals for China. Therefore, this paper explores the factors of CO2 from the perspective of CO2 mitigation potentials (CESP) and analyzes the heterogeneity of each factor. We first employ the DEA-IDA model framework to analyze the CESP and influencing factors of each region, and then use geographically and temporally weighted regress to analyze the spatiotemporal heterogeneity of influencing factors, the efficiency, coal proportion, energy intensity, per capita GDP, urbanization rate, electrification rate, trade, economic structure, and climate conditions. The research results show that: (1) for 1 unit increase in per capita CO2, the per capita CESP increases by 0.56 units. The CESP of the central and western regions is greater than that of the eastern regions, and the improvement of resource utilization efficiency can achieve the peak in advance. (2) Per capita GDP and energy intensity are the main positive factor and negative factor, respectively, and the impact of efficiency changes on CESP is mostly positive. (3) Efficiency is the most influential factor affecting the CESP; among them, a 1% increase in efficiency in Hebei can reduce the CESP of 62.47 Mt. In regions dominated by clean power, the impact of electrification rates is negative. The rest of the factors also showed spatiotemporal heterogeneity. Our findings have important policy implications, especially in how to effectively reduce carbon emissions to formulate more appropriate policy.