On April 2, Zheng Weibin, a researcher at the Smart City Research Institute of the Beijing News, issued a document titled “The Blockchain Reshapes Digital Identity and Opens 100 Million Market Disputes”. According to the analysis of the article, smart cities need a unified digital identity. At present, digital identity has been promoted in some countries. The mainstream scheme is based on the eID scheme of cryptography, but the scheme has the problem of “data island” at the national level. Digital identity also faces enormous security and privacy issues. The article points out that this is precisely where the blockchain and other emerging technologies come into play. The technology of successful cryptocurrency offers great potential for protecting billions of connected devices and the growing smart city network. Encrypted, secure, decentralized, and consensus-driven blockchain technologies not only protect end-user identities, connect devices and critical infrastructure, but also provide secure communication and data transfer across the network to prevent it from being compromised or tampered with.