Vietnam has a long coastline of 3260 Km running from north to south, ranking 27th in the world. There are 29/64 coastal provinces and cities with a population of about one-half of the country's population [1]. So assessing shoreline changes [15] is important for policy planning and taking appropriate measures in accordance with the changing situation of natural conditions. In particular, the area from Tien Giang to Soc Trang Province has many coastal aquacultures and the living of many coastal people. There are methods for evaluating shoreline changes by combining available software such as IDRISI, ArcGis, Snap, eCognition to process Landsat 8 satellite image so the method has many manual stages. In this paper, we propose a new approach for assessing coastline changes by using Raster package with programming in R language on Landsat 8 satellite images to reduce manual stages. The results have assessed the shoreline changes with our choice from Tien Giang to Soc Trang province within 4 years from 2014 to 2018 by analyzing on 2 scenes of Landsat 8 satellite images on April 22, 2014 and December 02, 2018 archived rather well.