Blockchain technology could be the most disruptive innovation since the Internet era. Blockchain encrypts data based on complex cryptography, and use decentralized algorithms to make the most troublesome security trust problem resolved in the Internet. It can enable users to reach a consensus without the intervention of third parties, and resolves the problem of trust and data value transferring on the network. Owing to the ecological business model design that makes it autonomously. The digital citizen card in Taipei City is similar to the use of blockchain in identification. There is a lot of room for development and imagination for blockchain in the future.