With the continuous promotion of "dual carbon" driven by technological innovation，leading enterprises find themselves in a dilemma. They must not only comply with the requirements of green legitimacy but also uphold crucial differentiators in breakthrough key technologies. To address this issue，based on the optimal distinctiveness theory，we analyzed the case of Broad and constructed an optimal differentiation process model for leading enterprises to continuously make breakthroughs in key green technologies. Our findings revealed that:First，in their pursuit of breakthrough key green technologies，leading firms exhibit a progressive consolidation of legitimacy，moving from initial creation to augmentation and，finally，expansion. Concurrently，their differentiation evolves from a technology-based focus to an institutionally-defined strategy，encompassing technological definition，category creation，and ultimately，institutional design. Second，this staged evolution of legitimacy and differentiation results in a corresponding shift in the optimal differentiation mechanism. This mechanism transitions from threshold orchestration to integrative orchestration，and ultimately，to compensatory orchestration. Third，this refined differentiation mechanism facilitates a transition in technological breakthroughs，progressing from multi-dimensional advancements to enhanced value creation—a shift from upstream to downstream value—culminating in fundamental technological innovation that alters the very foundation of the system. This paper not only expands the theoretical boundaries of the breakthrough process of key green technologies from the perspective of optimal distinctiveness，but also enriches the optimal distinctiveness theory from the context of technological breakthroughs.