Based on a sample of listed companies in the photovoltaic industry, and taking the “531 New Policy” as the research context, the PSM-DID analysis found that the overall level of R&D investment has increased after the subsidy withdrawal. Based on the organizational ecology perspective, fuzzy set qualitative comparative analysis (fsQCA) was used to discuss the synergistic influence mechanisms of six factors from two dimensions of "environmental pressure-organizational adaptation" and to identify three mechanisms that enterprises in the PV industry increased their R&D investment after the subsidies were withdrawn. The paper innovatively examines the impact of policy environment (changes) on firm innovation from the perspective of “phasing-out subsidies”; at the same time, it explores the interaction mechanism between “environmental logic” and “organizational logic” in the organizational ecology framework. The findings of the study provide important practical insights into the innovation decisions of firms in the context of policy changes.