Abstract: Detection of the coastline change caused by reclamation projects and hydrodynamic environmental impact analysis of the Caofeidian sea area for nearly 20 years are conducted by means of ArcGIS， and using 4 satellite images including Landsat TM and HJ-1A /1B， and the underwater geomorphologic map in 2003.Analysis results show that in the first 10 years， the coastline advances slowly， and the maximum distance to the sea in some areas is only about 1.3 km; and the reclamation scale is small， and is more limited within 0 m contour. The coastline has advanced towards the sea significantly in the last 10 years， and the reclamation area has been deepened into the 0 m contour but within the -5 m isobath. The current reclamation has little impact on the hydrodynamic environment around. Deep troughs show good stability though there is scouring and silting between the internal and external of offshore bars. According to the reclamation plan for the next decade， there is a need to strengthen the monitoring， including remote sensing means. Research of cumulative impact of several reclamation projects in Bohai Bay on the Caofeidian sea area also should be carried out in the future.