With the promotion of electric power reform in China, distributed energy participating in power market transaction becomes possible. However, due to the characteristics of transaction decentralization, multiple energy synergies, information symmetry and the large quantity, the transaction cost and the risk of information leak increase significantly, which inhibits the enthusiasm of distributed energy to participate in electric power transaction. The block chain has been widely used in finance, logistics and other industries because of its decentralized data processing. In this paper, the characteristics and infrastructure of the block chain is analyzed and the distributed energy trading frame work based on the block chain is built. The result shows that block chain has significant effect on the information security of the energy transaction.