Using GraphRAG and PageRank, this study builds a knowledge graph of Shanghai’s S&T policies (1949~2025) and identifies key policy nodes across seven historical stages.Findings reveal three evolutionary patterns: actors expanded from few to many, coordination evolved from simple to complex, and policy targets broadened from narrow to wide. The study pushes the empirical timeline back to 1949 and introduces LLM-driven relation extraction with global centrality measurement to S&T policy research.