In order to assess ecological risk caused by land use changes in a region with a rapidly developing economy, based on remote sensing data of land use in Jiangsu coastal areas in 1990, 2000, 2010, and 2015, this study analyzed the land use changes and its transformation, quantitatively supported by Geographic Information System(GIS). The present study built an ecological risk index based on the landscape disturbance index and vulnerability index, and then the spatial and temporal dynamic changes of landscape ecological risk were quantitatively evaluated using geostatistical analysis and spatial autocorrelation analysis. The results showed that the ecological security of Jiangsu coastal areas had improved, and the average ecological risk value of the entire region decreased from 0.1563 in 1990 to 0.1529 in 2015. In the last 25 years, the moderate ecological risk level covered the largest area of the study region; the higher ecological risk level was mainly distributed in the cultivated land of the southwestern region and the waters of the western region of the study area, and its area decreased. Grade reduction zones of ecological risk were mainly concentrated in the higher ecological risk area, moderate ecological risk area, and lower ecological risk area. Meanwhile, grade increase zones of ecological risk were mainly concentrated in the lower ecological risk area and moderate ecological risk area, that is, the grassland and waters of the eastern region of the study area and the cultivated land of the southwestern region. The rapid development of the port industry and new coastal town resulted in the intensification of land use change, which damaged the balance of the ecosystems. The overall spatial difference of ecological risk in the study area had increased, showing the high-high aggregation and low-low aggregation in the local area. The area of high value primarily aggregated gathered south along the western boundary of the study area, and the low value aggregation region was largely distributed in the northeast of the study area and the eastern coastal areas. In addition, arable land, waterbodies, and construction land were the main sources of ecological risk in the study area. The results of the present study could provide a scientific theoretical basis and reliable technical support for the realization of land sustainable utilization, promoting the coordinated development of land use and environment protection, and the policy making of ecological risk management.