The Philippine Sea Plate has an extremely special tectonic background.As an oceanic plate,it is almost entirely surrounded by subduction zones with complex internal tectonic features.On the basis of enormous published literature,this paper offers a comprehensive overview of the tectonic and evolution history of the Philippine Basin and the Kyushu-Palau Ridge (KPR) in the Philippine Sea Plate,and discusses the geological features of KPR.Referring to relevant definitions of various "ridges" stipulated in United Nations Convention on the Law of the Sea,so the KPR is believed to be a remnant arc formed during the opening of the Parece Vela and Shikoku Basins in the Philippine Sea Plate.It is a submarine ridge on oceanic plate rather than a submarine elevation.And thus,it is not a natural component of the Japan continental margin.