Abstract: Based on high resolution seafloor bathymetry map, we divided the Southwest Indian Ridg （SWIR） （11.88°E—66.75°E） into six regions. In each region, we estimate the variation of the axial morphology, and the basement subsidence curve over the flanks of the spreading ridge, which can be used to indicate the spreading process of the SWIR and how it was affected by the hot spot. The result shows that: ① For the entire SWIR, axial uplift accounts for 13.38%, axial rift accounts for 82.8%, and flat transitional shape accounts for 3.82%, the areas at 19°E, 36°E, 41.2°E, 43.7°E, 50.4°E, 64.5°E have focus magmatic ridge representing axial ridge uplift; ② The area between the Eric Simpson-Indomed transition faults （39.4°E—45.77°E） shows axial valley with anomalous shallow bathymetry and asymmetrical anomalous low basement subsidence rates between north and south. Therefore, we believe that the area between the Eric Simpson-Indomed transition faults has been significantly affected by the hot spots. Compared with the subsidence rate north of the spreading ridge, the anomalous low subsidence rate in the south indicates that the interaction between the hot spots and the ridge is characterized by the hot spots flowing upward from the south of the SWIR to the bottom of the lithosphere, and then interact with the lithosphere.