Hydrochemical quality of groundwater in chahardoli’s basin located in southeast of Iran has been investigated in this study. 66 water samples were taken in an area of 340 square kilometers and analyzed for the concentration of major ions, electrical conductivity (EC), and pH. Spatial distribution maps of ions concentration were shown an increasing pattern in central of basin. Due to high concentration of ions most of the water samples are not categorized in suitable ranges for drinking use. For assessing the suitability of groundwater for irrigation different indices were used. Except 7 water samples, all other samples have acceptable quality for irrigation. The dominant type of groundwater in the area is Ca-HCO3 that is common type of fresh waters in Ian. Finally, The groundwater quality map for irrigation purposes was classified by using GIS. Deepening the wells for more pumping water because of drawdown water table during recent years has caused entrance water form lower aquifer with high EC to wells. We encounter with water scarcity for irrigation now and in the future water quality may another problem.