Census of Marine Life (CoML) is a growing global network of researchers in more than 80 nations engaged in a tenyear initiative to assess and explain the diversity, distribution, and abundance of life in the ocean and explain how it changes over time. The Census is divided itself into three parts. History tells us what lived in the ocean. Exploration tells us what lives in the ocean now. And by combining what we learn about historical trends with our knowledge of what lives there now, we can begin to formulate an answer to the core question of what will live in the ocean of tomorrow. The background, strategy, research projects, new technologies and methods, and the preparation and development of the Chinese CoML are introduced in this paper, which is expected to be useful for research and policymaking in related areas.