Abstract: The western Pacific has the most active plate tectonic processes and land-ocean interactions. The Caroline Basin is a small plate formed between the Tethys and the Pacific, currently located at the throat of the Indonesian seaway, and takes a large area of the western Pacific warm pool. The Caroline plate is rather complex topographically and is characterized by ridges and relic spreading centers. The plate is bordered by young active subduction zones and active spreading centers, and strongly interacts with the surrounding Philippine Sea plate, the Pacific plate, the Ontong-Java large igneous province, and many deep trenches. Therefore, it is an ideal place for studying process and dynamics of initiation of subduction and seafloor spreading, as well as the interaction of the solid earth with seawater. In the past, the investigation of the Caroline Basin was done mostly in the 70—80 s of last century. So far, many controversies remain unsolved on the nature and genesis of some tectonic units, and the interactions among multiple geospheres were seldom explored. The implementation of the major research project on " Multi-sphere Interaction of the Western Pacific Earth System” supported by the National Natural Science Foundation of China greatly accelerate the pace of marine research in the Western Pacific region. In this project, we conduct comprehensive geophysical and geochemical analyses of the tectonic boundary process of the Caroline Basin and the extent of serpentinization of the uppermost lithospheric mantle in the basin. We also examine the coupling between the deep process in the lithosphere and the shallow process on the seabed, in particular the relationship between water and heat flux. Based upon the research, we propose in this paper an evolutional model for this unique oceanic micro-plate and its tectonic boundaries. Further research activities, including scientific ocean drilling, are recommended.