In this study, groundwater of Ardabil aquifer quality in terms of drinking and agricultural, was evaluated. For this purpose, 76 wells including 32 drinking wells and 44 agricultural wells were considered. The results indicated that groundwater quality on the Water Quality Index (WQI) is in good condition. Based on the standards of the World Health Organization (WHO) and Institute of Standard and Industrial Research of Iran (ISIRI), 10.5 percent of the wells have nitrate levels above the limit in the wet season; but in the dry season, about 29 percent of the wells had nitrate values higher than allowable level. In order to assess the quality of groundwater for agricultural use, as well as the Wilcox diagram and other parameters of sedimentation and corrosion including: Langelier saturation index (LSI), Ryznar Index (RSI) and Puckorius (POR), magnesium hazard (MH), permeability (I), the remaining sodium percentage (RSC), sodium adsorption ratio (SAR) and the percentage of sodium and chlorine were used. The results showed groundwater of this aquifer are corrosive and use it in urban water supply systems, causing illness and various problems caused by corrosion of pipes and the, the human will. The use of these waters, for agricultural purposes will cause problems in metal fittings of sprinkler irrigation systems