[Objective] The dynamic changes of soil erosion intensity and its spatial distribution in the source region of the Yellow River during 1999-2018 were studied to provide data for ecological environment construction and soil and water loss management in the region.[Methods] The dynamics of soil erosion in the region were analyzed based on the monitoring data in 1999, 2011, and 2018.[Results] Compared with 1999, the areas of soil erosion increased to 1.89×10⁴ and 1.01×10⁴ km² with an increase of 126% and 67.33% in 2011 and 2018, respectively, indicating that the area of soil erosion had increased in 2011 and then decreased until 2018. From 1999 to 2018, the area without any change in soil erosion intensity grade accounted for 77.97%, and the areas with decrease and increase in soil erosion intensity grade were 19.33% and 2.70%, respectively.[Conclusion] The increasing area of soil and water loss can be attributed to climate warming and drought, and grassland degradation was caused by unreasonable human activities. A number of major ecological protection, restoration and construction work should be carried out to improve the quality of degraded grassland and regional ecological environment.