Promoting the development of "specialized，refined，distinctive，and innovative" （SRDI） small and medium-sized enterprises is a classic policy-instrument-driven development paradigm. The key to SRDI policy optimization lies in considering the dynamic alignment among policy instrument，policy theme，and policy effectiveness. Drawing from public policy evaluation theory，this study employed text mining and quantitative text analysis to conduct a comparative analysis and assessment of 466 SRDI-related policy texts from the Yangtze River Delta and Pearl River Delta regions spanning 2006 to 2024. The results indicated that the selection and configuration of policy instruments face issues including preferential biases，overuse，omission，and disproportionate allocation； the policy themes and anchoring of development positioning suffer from lag effects and insufficient synergy； and there is a pathway for further optimization in policy effectiveness. In response，the continuous adjustment and optimization of the policy system supporting the development of SRDI enterprises should focus on three key aspects:optimizing the structure of policy instruments，innovatively rethinking policy themes and design，and effectively addressing policy gaps. By leveraging these three aspects，the reform and innovation of policies for SRDI enterprises can be advanced through a systematic approach. This study aims to provide an optimization pathway for enhancing the appropriateness and scientific rigor of the SRDI policy design，and to offer methodological references for public policy research as well.