Abstract: Abstract: Through the Hedong Sandy Land, the Ulanbuh Desert, and the Kubuqi Desert, Ningxia-Inner Mongolia Reach of the Yellow River suffered from serious blown sand hazard. A mass of aeolian sediment deposited in the Yellow River and brought a serious siltation in the Yellow River. It is in urgent need to develop a warning system to reveal the spatial distribution of threshold wind velocity for wind erosion in the watershed of the Ningxia-Inner Mongolia Reach of the Yellow River. The aim of this research is to provide theoretical guidance to prevent the blown sand hazard in this region. In this research, integrated Normalized Difference Vegetation Index (NDVI) data set and the observations in the study area, the threshold wind velocities of different surfaces were calculated, and spatial distribution of threshold wind velocity for wind erosion in the study area was revealed. Firstly, using a map of NDVI, we calculated the vegetation coverage, frontal area, and roughness length in the study area. Then, the frontal area was used to calculate the threshold friction velocity by the vegetation influence function. With tested calculation method of threshold friction velocity using the observed sand flux data, we found the simulated errors were all small. Based on the truth that the wind profiles above the study area all obeyed logarithmical functions, we estimated the spatial distribution of threshold wind velocity for wind erosion in the watershed of Ningxia-Inner Mongolia Reach of the Yellow River. We found that most of the regions that with wind erosion risk were near the Yellow River. At last, this paper proposed a method that using the maximum NDVI in this year to predict the threshold wind velocity based on the relationship between NDIV in the next windy season and maximum that in this year. We hope this research would provide some theoretical advises for predicting the wind erosion hazard in the watershed of the Ningxia-Inner Mongolia Reach of the Yellow River.