<p>James O’Connor and Kohei Saito, as representative figures of contemporary ecological Marxism, are both committed to excavating and elucidating Karl Marx’s ecological thought. They both emphasize the incompatibility between capitalism and ecological sustainability and have each outlined visions of a future ideal society. However, they diverge in their approaches to substantiating Marx’s ecological theory, diagnosing the roots of ecological crises under capitalism, and exploring concrete pathways for resolving such crises. These differences give rise to two distinct research trajectories, characterized respectively as “theoretical reconstruction” and “classical interpretation.” This paper adopts a methodological approach that combines comparative analysis with textual interpretation. On the basis of a systematic review and in-depth examination of the similarities and differences between the two theorists, it offers a dialectical assessment of the value and limitations of their ecological Marxist theories. Such an inquiry not only helps to clarify their intellectual divergences and theoretical particularities, but also contributes to a deeper understanding of Western ecological Marxism.</p>