Abstarct: The study area of Neyshaboor, with an area of 7,386 square kilometers in Khorasan Razavi province, has an elongated shape surrounded by mountains. To conduct hydrogeological and hydrogeochemical studies, data from the water level of piezometers located in the aquifer, as well as 66 qualitative water samples from existing extraction wells in the study area, were used. The potentiometric maps and flow direction indicate that the main recharge of the aquifer comes from the east, northeast, north, and a small part of the southern regions. The general direction of groundwater flow is from the east and southeast towards the west, which is aligned with the surface flows of the Kal Shur river. The maximum hydraulic gradient of the groundwater level is observed in the Salari area in the southern part of the aquifer, while the minimum hydraulic gradient is found in the Kal Shur area in the southwestern part of the aquifer. According to the hydrograph of the Neyshaboor aquifer, the overall trend of the groundwater level is declining, showing an average long-term drop of 0.73 meters per year. baxsed on the map of electrical conductivity changes, the electrical conductivity increases in the direction of groundwater flow from the recharge area to the discharge area, ranging from 21.9 μS/cm in the eastern part of the aquifer to 16740 μS/cm in the western part of the aquifer. Hydrogeochemical and isotopic studies of the study area indicate that the primary source of groundwater in the area is mainly local precipitation with Mediterranean and polar origins, and the evaporation process has not significantly affected the isotopic behavior of these samples. baxsed on this, the salinity of the groundwater samples is not due to evaporation but may result from the dissolution of evaporites or slight infiltration of saline water from surrounding basins and mixing occurrences.