In the early years, the rising of the sea level, which is a part of natural treatment, destroyed many buildings, arable lands, residential and commercial areas. It seems that the main reason of these destructions is the diminishing of the legal setback efficiency and the proceeding of human activities. The aim of this study is to introduce the appropriate setback for southern coast of Caspian Sea (Gilan province) on the basis of critical levels of Caspian Sea and the results of coastal vulnerability regarding sea level rise. This setback is composed of two parts, vertical buffer and horizontal buffer. In this study, CVI method (coastal vulnerability index) was used for coastal vulnerability assessment. In this method, five variables were employed as in two sub-indexes, natural and human-induced sub-indexes. The final map is divided into four categories, from low to very high vulnerability. Finally the mean distance from the very high vulnerability category to vertical buffer boundary in every district is introduced as the horizontal buffer.