Consortium blockchain technology is the main position of China’s blockchain development and application. The traditional consortium blockchain application has some bottlenecks, such as heterogeneous underlying technology platform, high application technology threshold, high cost of chain formation, and difficult operation and maintenance supervision, which restrict the development of blockchain technology and application. This study proposes the construction mechanism of a public infrastructure of blockchain, named as blockchain-based service network (BSN), and expounds on the technical architecture and implementation of BSN. The BSN has become a commercial platform in China since April 2020. It can reduce the cost of blockchain development, deployment, operation and maintenance, interaction, and supervision. BSN is conducive to the promotion and application of blockchain technology to enterprises, governments, industries, and other fields, and will provide reliable and controllable public infrastructure for the construction of innovative smart cities and the development of digital economy in China.