As one of the most concerned Internet technologies in recent years, blockchain technology is in the process of accelerating its evolution and maturity. The blockchain is gradually integrated with other Internet technologies and applied in many industries, providing decentralized solutions for various industries, realizing innovative storage models, and building a new trust system. As one of the largest international standardization organizations, the Telecommunication Standardization Sector of the International Telecommunication Union (ITU-T) has published standards with great influence in the world, and there are many standards published and under development in the field of blockchain technology, and the types of standards are abundant. This paper first introduces the organizational structure and workflow of ITU. Then it introduces study and achievements on blockchain, including the focus group established by ITU-T and the standards published and under development by multiple study groups. It makes a statistical analysis of the standards, and expects that the blockchain standards will be more diverse in the future to meet the needs of industrial development.