Abstract: Against the dual backdrop of the accelerating global energy transition and rising geopolitical risks, analyzing the current status and development trends of China’s overseas oil investment is of great significance for ensuring national energy security and promoting high-quality development in the oil industry. By comprehensively considering the energy transition process and geopolitical risk elements, this study constructs an overseas oil investment evaluation index system covering five dimensions, including oil resource environment, geopolitical environment, economic environment, international cooperation environment, and energy transition environment. A combined super-efficiency DEA-Malmquist-Tobit regression model is employed to evaluate the efficiency of China’s investment in key oil resource countries along the Belt and Road from 2016 to 2022, disaggregated by region and year. Specifically, the super-efficiency DEA model is used to evaluate the current status of China’s overseas oil investment, the Malmquist index to analyze the dynamic changes in investment efficiency, and the Tobit regression model to examine the impact of energy transition and geopolitical risks on China’s overseas oil investment efficiency. The study shows that China’s overseas oil investment efficiency in key countries along the Belt and Road remains relatively high, with overall technical efficiency generally above 1.0. though it has declined in the past two years due to factors such as geopolitics and energy transition. There are significant regional differences in investment efficiency, with higher and more stable efficiency in the CIS region and Southeast Asia, basically effective performance in West Asia, and generally low efficiency in South Asia and Africa. The acceleration of the energy transition process （e.g., carbon tax policies, renewable energy substitution） has a significant negative impact on investment efficiency, while the impact of escalating geopolitical risks on investment efficiency is complex. China should optimize its overseas oil investment layout by prioritizing Southeast Asia and CIS regions, which boast substantial resource potential and relatively high investment efficiency, and strengthen risk-hedging mechanisms in South Asia and Africa. Concurrently, energy transition factors should be integrated into investment decision-making frameworks, and low-carbon technology cooperation should be promoted to mitigate transition-induced uncertainty risks. The study provides theoretical foundations and methodological support for the efficient advancement of China’s overseas oil investment and energy security assurance under the new situation.