Abstract: Three North Regions have been the key areas of ecological construction and ecological civilization. To provide scientific basis for the following ecological construction, vegetation change monitoring in the Three North Regions was carried out. Based on the long-term NDVI data, the trend analysis, coefficient of variation and Hurst index analysis were applied to simulate and analyze the changing characteristics and the sustainability of NDVI trend in the area from 1998 to 2018. The results showed that: during the period of 1998—2018, the vegetation in the areas improved, and the boundary between the rising area and the falling area of NDVI was roughly bounded by the 200 mm precipitation line. The improved area of Shanxi and Shaanxi was more than 95%, while less than 50% of Xinjiang was improved. In recent 20 years, NDVI data of more than 80% of the area fluctuated obviously, and the fluctuating area and stable area could be roughly divided by the 400 mm precipitation line, and the fluctuation in Xinjiang was most severe. The average value of Hurst index is 0.47, and the trend of NDVI change in more than 90% of the area was difficult to maintain for long time. From 1998 to 2018, the vegetation in Three North Regions has improved, but the sustainability is not strong. It is necessary to strengthen the ecological restoration and protection of vegetation to ensure the sustainability of ecological civilization construction.