As an ecotone between the ocean and land, coastline plays a crucial role in ecological functions and resource value. Its dynamic changes are directly linked to green development of marine economy, marine ecological security and the wellbeing of coastal communities. It is the "lifeline" of marine economic development. By using multitemporal Landsat satellite remote sensing images, combining with remote sensing interpretation and GIS spatial analysis techniques, spatiotemporal changes of Rongcheng coastline from 2000 to 2022 have been systematically analyzed. It is revealled that the total length of Rongcheng coastline has increased 53.81km during this period. Artificial coastlines has expanded significantly, while bedrock and sandy coastlines initially has decreased before stabilizing. The period from 2000 to 2005 is the most rapid growth of artificial coastlines, with an increase of 100.94km. It is primarily driven by human activities, such as port construction and aquaculture expansion. This rapid growth has not only altered natural morphology of the coastal zone, but also profound impacts on the coastal ecosystem. Accompanying with increasing awareness of ecological and environmental protection, development activities in Rongcheng coastal zone have gradually become more rational, and the rate of coastline changes has slowed. It is recommended that dynamic monitoring of coastal zone changes should be strengthened, spatial layout of the coastal zone should be optimized, and more intensive and efficient development and utilization of coastal areas should be promoted. It will ensure that precious coastal resources in Rongcheng city will become a vital foundation for "Free Breathing·Comfortable Rongcheng".