Rapid developments in technological innovation and industrial policy practices are observed globally. How credit interest subsidies can more effectively alleviate the financing constraints of strategic emerging industries (SEIs) is recognized as a critical issue in building China's modern industrial system. A profit-sharing mechanism and an endogenous linkage mechanism of credit interest subsidies were innovatively incorporated into a DSGE analytical framework. A DSGE model was constructed to include heterogeneous firm financing constraints and profit-sharing. The differentiated pathways and effects of exogenous versus endogenous credit interest subsidy policy mechanisms were analyzed. It is found that the endogenous subsidy mechanism with dynamic linkage between "interest subsidy and credit scale" can significantly reduce the crowding-out effect of SEI technological progress on traditional industries by triggering an automatic stabilizer function. The necessity of shifting policy design from fixed ratios to precise dynamic adjustments is thus confirmed. An "intensity paradox" is identified in credit interest subsidies, whereby excessive subsidies weaken long-term effectiveness through fiscal negative feedback loops. Quantitative evidence is provided for identifying the optimal intensity boundary for policy effectiveness. The state-owned enterprise profit-sharing mechanism is internalized as a funding source for interest subsidies. A virtuous cycle of "technological progress→profit growth→fiscal revenue increase→subsidy expansion→industrial development→subsidy sustainability" is thereby established. Through phased dynamic adjustments of profit-sharing ratios, the dilemma between short-term incentives and long-term sustainability is effectively resolved. It addresses the "industrial misallocation" and "entity misallocation" contradictions in China's credit allocation, and puts forward policy recommendations to construct a dynamically adjusted profit-sharing mechanism and a linkage mechanism between "interest subsidy and credit scale", providing a solution for optimizing credit allocation, resolving the financing dilemma of strategic emerging industries, and promoting industrial synergy.