This paper briefly summarizes the Japanese IODP activity and science plan. As one of the IODP core technology, the riser drilling vessel “Chikyu” is capable of drilling 7,000m into the ocean floor in deep sea areas with a water depth 4,000m. It is capable of drilling to the seismogenic zone and the upper mantle, and is helpful to reach Japanese IODP scientific goals . Japan's IODP scientific goals mainly has three big scientific subjects and eight research goals, of which, three big scientific subjects involve mantle processes and the Earth system evolution; crustal process and the Earth system evolution; and dynamics and mass circulation in subduction zones and Earth system evolution. The eight major research topics are : ①understanding coremantle processes, by deep drilling into a large oceanic plateau in the Western Pacific; ②detailed investigation of material circulation during greenhouse Earth, and the transition process from greenhouse to icehouse environments, by drilling Cretaceous to Cenozoic sediments in the Pacific, ③understanding the process of continental crust formation by deep drilling into oceanic arc, ④Understanding the process of oceanic lithosphere formation by deep drilling of the back arc spreading system, ⑤understanding of continentoceanatmosphere linkage, by drilling in the marginal seas and continental slopes of Asia, ⑥investigation of the carbon cycle and the deep biosphere in accretionary prisms, ⑦investigation of the mechanism and cycles of great earthquakes, tectonics, and mass circulation in convergent plate margins,and ⑧biology of extreme microorganisms living in deep accretionary prism environment.