Abstract: The Ninetyeast Ridge (NER) developing in the Eastern Indian Ocean, extending from the Bengal sedimentary fan to the Brocken Ridge, is the longest Lineament in the world. The formation mechanism of the Ridge is related to the multi-stage evolution of the East Indian Ocean during Late Cretaceous to Cenozoic era. The length of the Ridge is more than 5 000 kilometers, and the tectonic settings in the northern and southern regions are very complex, showing obivous different geophysical characteristics in different segments. This study analyzed geological and geophysical data including the morphology, shallow structure, gravity and magnetism, crustal thickness, and ocean floor age of different sections of the ridg. The data, combining with the evolution history of seafloor expansion in the Eastern Indian Ocean, are uesd to explore the genetic mechanisms of different segments of the Ridge. The results show that the formation of the NER is related to many factors, such as intraplate hot spot activity, the interaction of mantle plume and mid-oceanic ridge, plate expansion and the transition of the expansion center, as well as transform faults, and is the result of the combination of multiple geological processes. The ridge to the north of 2°N may be formed in the interior of Indian Plate far away from the spreading center, which is related to intraplate volcanism. The part to the south of 18°S was formed near the transform fault between Indian Plate and Antarctica Plate. The central region between 2°N and 18°S is the most complex, and it is speculated that the formation of the region is influenced by some factors such as the interaction between the Kerguelen hotspot and the Wharton spreading ridge, and multiple mid-oceanic ridge jumps below the Ridge. We suggests that the central region of the Ridge is a key area for understanding the genetic mechanism of the Ridge, solving major scientific problems such as structural evolution and dynamic mechanisms of the Ridge, and interactions between mic-oceanic ridge and mantle plume. Finally, we proposed that the only way to solve some major scientific problems mentioned above in the near future is to carry out geophysical survey and drilling work in the central region of the Ridge, and to reveal the material composition and formation age of basement rocks at different locations in the central region of the ridge.