Abstarct: Qaresoo Plain with an approximate area of 1600 km2 and with coordinates of 54° 00' to 54° 54' eastern longitude and 36° 36' to 36° 59' north latitude is part of the Gorgan Basin. It is located in the western part of Golestan province and south-east of the Caspian Sea. The exiting groundwater in this area is of vital important. From the hydrogeological point of view, it consists of both confined and unconfined aquifers. The saline water of Caspian Sea and salt plain exist in west and north of the plain. The main purpose of this study is to study the hydrogeological and hydrochemical characteristics of the both aquifers. In order to study the hydrogeological characteristics, the data of water level variation in 16 piezometer wells in the unconfined and 41 in confined aquifers of the plain is used. The general groundwater direction in both aquifers is from east and south to east and north-east of the plain. According to unit hydrograph of 15 years, a 1.6 m and 5.77 m reduction in the groundwater level was observed in confined and unconfined aquifer, respectively. According to the water balance equilibrium equation for confined and unconfined aquifers in Qaresoo Basin, in 2009-2010, the volume of reservoir’s changes for the confined and unconfined aquifers is -2.66 and -1.28 Mm3, respectively. baxsed on the hydrochemistry analysis of 41 water samples from operating wells and sea water, the groundwater quality is affected by the aquifer water withdrawal and intrusion of saline water, especially in west and north of the plain. The electrical conductivity is increasing along the direction of flow from the recharge point to the discharge point in both aquifers, which is changed from 400 to 2200 µS/cm and 700 to 2780 µS/cm in the confined and unconfined aquifers, respectively. The enhancement in salinity of these aquifers is mainly due to salt water intrusion from Caspian Sea and salty plain in north of the area.