Abstarct: Saline water intrusion is an important and noticeable phenomenon in coastal aquifers that results in the salinization of fresh groundwater. Minab plain that is located in Hormozgan province and adjacent to the Persian Gulf, is one of the most important coastal plains in the south of the country that has been affected by saline water infiltration. Regarding the two-laxyer nature of Minab plain aquifer, for hydrogeology and hydrogeochemistry investigation, data of 39 piezometers in water table aquifer and 12 piezometer in confined aquifer with total 68 water samples from pumping wells in the land and sea have been used. The equipotential and flow direction maps of the plain indicates that the aquifer is dominantly recharged from north and northeast parts and southern elevated parts and the flow direction is toward the center of the plain. In recent years, with over withdrawing and increasing the number of exploitation wells, especially in eastern and central parts of the plain lead to change of the Hydraulic gradient in the western and southern parts that result in sea water intrusion. According to the unit hydrograph for water table and confined aquifers, the average level of piezometers is declining, that indicating the negative water budget. According to the equidecline map of Minab plain, the highest decline is observed in the eastern and central parts of the plain due to better groundwater quality and the lowest drop observed in the northern and western parts of the plain owning to the low quality. Electrical conductivity distribution map shows that its value is highest in northern, northeastern, southern parts and some area of the northwest part. The lowest electrical conductivity is 1025 mho/cm that observed in eastern and central wells which have important role in drinking water supply and agriculture water in the state.also, the studies showed that the cause of salinity of wells in the northern area and parts of the eastern area of the plain is salt dissolution and the infiltration of saline water from evaporative formations adjacent to the plain. Hydrochemical and isotopic studies in Minab plain confirmed the occurrence of salt mixing, dissolution and seawater infiltration as a source of salinity.