The information asymmetry in financing has long been a challenge for small and medium-sized enterprises (SMEs), making it difficult for banks to accurately assess their credit risks. Moreover, in the traditional supply chain finance model, core bottlenecks such as data silos and the ineffective transmission of credit persist, greatly constraining financing efficiency and transparency. This study focuses on the application of blockchain technology in supply chain finance, exploring how blockchain can break through data silos, enable multi-tier credit circulation, and thereby enhance the financing efficiency of SMEs while reducing financing costs. Specifically, through normative analysis and case comparison, it examines how blockchain facilitates multi-tier credit circulation via digital debt instruments, builds trusted data pools to lower financing costs, and ensures data privacy in collaborative sharing. The findings indicate that blockchain technology can effectively rebuild the trust mechanism in supply chain finance, but its widespread adoption still faces key challenges such as technical interoperability, insufficient momentum for ecosystem development, and the absence of a legal framework. In the future, blockchain will integrate deeply with the Internet of Things (IoT) and artificial intelligence (AI), driving supply chain finance toward an intelligent, automated digital financial ecosystem.