Abstract: Extraction of the coastline is an essential task of environment monitoring and change detection in coastal area. Ca Mau cape, Ngoc Hien district is affected by coastal environmental change and the coastline has been subjected to specific modifications over many years. The cause is determined by three factors including erosion, stability and sedimentation. The pattern of coastline changes of Ca Mau cape, Ngoc Hien district was identified by using Landsat TM images acquired in 1995, 2000, 2005 and 2010. In this study we proposed a semi-automatic technique to extract the coastline.  The result shows that the changing of shoreline iscomplex in this area. In period 1995 to 2010, erosion process occurred highest in Tan An while deposit process occurred highest in Dat Mui, Ngoc Hien district. In the Western of Ca Mau cape, accretion process is over predominated while erosion is over predominated in the East sea of Ca Mau cape. This information is valueable to support the local government in assessing, monitoring and making plan for land use in this region