Abstract: It has been 20 years since the concept of digital ocean was put forward. Based on the key words of "digital ocean", the digital ocean research literature published from 1999 to 2018 in China National Knowledge Infrastructure (CNKI) Databaseis, searched the development process, subject participation, research quality and evolution characteristics of digital ocean research in the past 20 years using the knowledge mapping methods are summarized. The results show that the achievements of digital ocean research rapid grew in the past two decades, and the level of attention has gradually increased. The participating disciplines are centered on oceanography and cover many disciplines, the types of literature are comprehensive, but the quality still needs to be improved. The research topics are obvious, that is to follow the wave of information technology closely. After experiencing the rapid development stage, the current digital ocean research has entered a relatively stable stage, but there is still space and necessity to explore in the research content, methods and technology. It is analyzed that in the future, the research of digital ocean should be developed in the direction of globalization, application, refinement and intelligence, so as to enter a new research climax.

Key words: digital ocean, mapping knowledge domain, 908 special projects, globalization, intelligent ocean