Supply chain finance has played a positive role in solving the financing difficulties of small and medium-sized enterprises. However, in the actual implementation process, there are still problems such as information asymmetry, doubts about the authenticity of trade background, and high operational risks, which seriously restrict the development of supply chain finance. However, block chain technology has the characteristics of de-centralization, data transparency, common maintenance and non-tampering. Applying this technology to supply chain finance can effectively solve the existing problems. Based on the research on the development status of traditional supply chain finance, this paper puts forward a new development mode of supply chain finance based on block chain technology, and through the analysis of typical cases, finally gives some policy suggestions for the development of block chain supply chain finance.