Abstract: In order to reveal the siltation and erosion dynamics of the Yellow River Mouth in the past 20 years for better understanding of the long-term dynamic changes of the deltaic coastline and their influencing factors, the general high tide line method and the methods of tassel transformation, supervised and unsupervised classification and visual interpretation are applied based on Landsat TM, ETM + and OLI remote sensing image data under ENVI environment. The coastlines of 11 phases with a time interval of every two years from 1998 to 2018 are extracted, and superimposed analysis is carried out in ArcGIS to complete the dynamic monitoring and coastline changes of the Yellow River Mouth for the past 20 years. The results show that the coastline changes of the Yellow River Mouth from 1998 to 2018 have obvious temporal and spatial differentiations. Deposition always coexists with erosion. In general, the total area of the Yellow River Estuary shows a trend of erosion towards inland area in the period from 1998 to 2018. The total length of the coastline decreased by 15.73 km and the total area decreased by 65.37 km². Sedimentation mainly occurs at the river mouth. Both the erosion and deposition have been gradually weakened since 2004. The southern part of the estuary was severely eroded. However, the erosion intensity has been weakened since 2010. No obvious erosion is observed along the coastline near the Gudong Oilfield. In recent years, human activities have also become an important factor in the evolution of estuarine coastline. This study provides a a scientific basis for rational planning of efficient development of the coastal resources.