Taiwan is the largest island of China. It faces the Pacific Ocean on the east where the bottom relief is very steep and most of the isobaths run parallel to the coast. At the places several tens of sea miles away from the coast, the depth increases abruptly to several thousands of meters. But at the northeastern corner, that is, to the east of Sandiao Jiao-Suao, there is an abrupt change in bottom topography, the isobaths are nearly perpendicular to the coast and run in the direction ESE, and the depth decreases rapidly from both the north and the south. Here is the submarine ridge as shown in Fig.1. North of the Philippines，the North Equatorial Current is divided into two parts, the main current(the Kuroshio) flows northward along the east coast of Taiwan, while the branch, besides partly entering into the South China Sea, flows northwestward and then northeastward along the west coast of Taiwan in summer. Accordingly, it may be considered that Taiwan Island is situated in the circumfluence of the Kuroshio and its branch in summer. The width of the main axis of the North Equatorial Current east of the Philippines is about 45 to 90 sea miles, and the east to west scale of Taiwan is about 80 sea miles, therefore, the latter is about 1.8 to 0.9 times as wide as the former. It goes without saying that, such a large island as the Taiwan Island，standing out against the flow pattern of the North Equatorial Current and the Kuroshio, must have a noticeable effect on the flow pattern of the Kuroshio. In the present paper, the hydrographical data collected in the period from 1927- 1973 in the region near Taiwan Island were analyzed mainly by qualititative treatment in order to study the topographic effects of Taiwan Island and adjacent bottom relief on the path of the Kuroshio.