[Objective] To study the changes in vegetation coverage around Ertan reservoir when it is filled with water, in order to provide the basis for assessing the impact of reservoir filling on vegetation growth surround the reservoir.[Methods] We used the dimidiate pixel model to predict the vegetation coverage of the study area in each November from 1999 to 2014 with the Landsat TM and environmental CCD images as the information sources. We then detected areas with obvious changes in vegetation cover through waveband operation and threshold segmentation.[Results] From 1999 to 2014, the vegetation cover in the study area increased year after year, and the high coverage area expanded greatly. However, the vegetation cover decreased in some areas due to human activities, soil erosion, farmland and landslide, which accounted for 19.5% of the total area; the region with obvious increase in vegetation cover accounted for about 39.8% of the total area, mainly concentrated areas near to the reservoir.[Conclusion] The Ertan reservoir had improved the growth of vegetation around, and the vegetation cover has increased year by year as a whole.