Abstract: The Duhe River Basin is an important water source area for the middle route of the South-to-North Water Transfer Project. The analysis of hydrological unit division and vegetation cover characteristics of the Duhe River Basin has important practical significance for identifying the ecological environment of the river basin. Based on SWAT distributed hydrological model and ArcGIS software, this paper analyzes the boundary extraction, sub-basin division and vegetation cover distribution characteristics of the Duhe River Basin by using moderate index method and mean statistical method. The results show that: ① the catchment area threshold is an important parameter for controlling the sub-basin extraction. The optimal index area for the water system extraction in the river basin is 10 000 hm² by the moderate index method. ② The annual average NDVI value of the Duhe River Basin is about 0.636, which is the medium-high vegetation coverage. Spatially, the vegetation coverage of the south bank is higher than that of the north bank; the vegetation coverage of the middle reaches is the lowest, with a gradual increase in the regions of the upstream and downstream. The highest annual average NDVI value is in the Huanglong River Basin and the lowest is in the Zhuxi River Basin, which shows obvious spatial heterogeneity. ③ The NDVI value of the Duhe River Basin is slowed down with the increase of the elevation, because the vegetation coverage of the high altitude mountainous areas is high. ④ The average annual NDVI values of the 12 sub-basins in the river basin between 2001 and 2016 showed a similar wave-like upward trend, indicating that the vegetation coverage of the whole basin is rising and the ecological environment is improving. And annually, the monthly average NDVI values of the sub-basins in the Duhe River Basin tend to be consistent, reaching the highest in August and the lowest in February.