Abstract: According to the different coverage of the surface vegetation, the study chose the reasonable vegetation index to reflect the effect of vegetation, and gave a certain technical support. Selected Hexi Corridor in Gansu Province as study area, the paper studied the correlation between different vegetation indices (PVI and RVI) and vegetation coverage, which was based on the NDVI value. The results showed the value of NDVI, the estimated vegetation coverage in the east, middle and west sections in the northern Hexi Corridor were 0.33, 0.31 and 0.42 respectively, the NDVI in the east, middle and west sections in the Qilian Mountains were 0.62, 0.62 and 0.37. The correlation between the PVI, RVI and different vegetation coverage indicated that the effect of RVI on reflecting the vegetation coverage in the high vegetation coverage area was significantly better than the effect of PVI. However, in the low vegetation coverage area, PVI was better than RVI because it can reflect the grain of sand nature of surface such as desert due to the little influence come from the soil background such as brightness and substance, and atmosphere.