Abstract: The Digital Ocean has gained remarkable achievement since China converted firstly the Digital Ocean from its conceptual to its construction. When summering the China Digital Ocean Prototype System， some issues are exposed gradually during the system constructions and operations. In this paper， architecture， functions and key technologies of the Digital Ocean Application & Service System which aimed at solving the issues are discussed in details. Practical demonstrations show that the system has applicative perspective in data sharing， information integration and visualization of ocean data.