Abstarct: Water leakage and internal erosion in the body and the earth's dam are the root causes of many problems and failures in these dams. There are several methods for controlling the penetration of the penetration, including the construction of an upright impermeable blanket, clay trenches, injection membranes, and cut-off-wall. Narmab Dam is a homogeneous earth with a height of 60 meters, a crown length of 807 meters and a reservoir volume of 115 million cubic meters. Due to the high depth of the alluvium in the studied dam, the removal of the desired laxyer is not possible until reaching the normal bedrock. The use of an injection seal is not possible due to the non-injectable nature of the laxyers. baxsed on this, a dam wall has been used for controlling leakage in the earthquake dam in the Narmab dam. The basis of this approach is to increase the length of the paths of the flow lines, thereby reducing the hydraulic gradient and the flow of infiltration. Cut-off-wall is designed baxsed on the geological status of rock mass and its physical and mechanical status and is of great importance for controlling leakage and damping. Considering the extension of the sealing wall inside the clay core for more optimal sealing, as well as considering the geological status and physical and mechanical characteristics of the rock, the interaction of the core and the pipe with the wall in different situations of static and dynamic loading Importance is abundant. The leakage analysis of dam and body construction is done by the finite element method using PLAXIS software in steady-state mode. With the help of this software, it is possible to plot current and potential lines and calculate flow rates for a certain section of the soil. In the Narmab dam, the concern is about the wall of the seals, and it is necessary to monitor the conditions and make arrangements to repair and strengthen the sealing wall if needed. In this research, the aim of this study was to investigate the sealing and sealing performance of the dam wall in the Narmab dam located in Minoodasht city of Golestan province, using the PLAXIS 2D software.