Assessing the marginal abatement costs (MACs) of emissions improves the understanding of the extent of current CO₂ mitigation and provides regions and industries with information on how to mitigate emissions cost-effectively. This study proposes a hybrid method to evaluate the MAC. It combines the strengths of bottom-up engineering methods and top-down economy-wide methods. A parametric directional distance function is employed to estimate the MAC from an economic perspective, and the abatement level is further incorporated to generate increasing curves, similar to the outcomes derived from an engineering perspective. In addition, this method takes into consideration whether the abatement level exceeds the abatement potential with current production technologies so as to provide a more realistic estimation of the MAC curves. The proposed technique is applied in estimating the carbon emission MAC in China’s petroleum industry. The estimation results indicate that (i) the MAC of China’s petroleum industry would change from 9821 to 16,307 yuan/ton when the abatement level increases from 1 to 50%; (ii) this industry would spend 36.5 to 42.5 billion Chinese yuan annually to achieve China’s CO₂ reduction target proposed in its Intended Nationally Determined Contributions (NDCs); (iii) assigning the CO₂ reduction targets based on the estimated MAC curves instead of the traditional grandfathering abatement target assignment would help to save China’s petroleum industry an additional 29.97 to 33.65% in abatement costs when achieving the NDCs. The MAC curves estimated in this study indicate more accurate relationships between abatement levels and abatement costs, and hence provide decision-makers in industries and governments with a more reliable instrument to determine the prices of emissions permits, total abatement costs, and implementation strategies in an emissions trading scheme.