Abstarct: Old Shahryar is a region where is limited to the Kan River in the east, Tehran-Karaj highway in the north, Robat Karim Highlands in the northwest and Arad Highlands in the south. 30-years investigations of groundwater level data measured at 42 selective piezometers located in this area, show that groundwater table levels in alluvial aquifer of this area, during 1984 to 2014 had a downward trend which resulted in the loss of approximately 15 meters of aquifer level. The highest drop of groundwater occurred in the northern plains (Shahryar and Shahre-Ghods counties, where high percent of gardens and farmland exist). This drop is mainly the result of excessive utilization of the aquifer and to a lesser extent in recent years has been the result of reduced rainfall. The loss of agricultural and urban development effects in central and southern parts (due to population migration) caused the groundwater pumping being less and due to feeding of plains by wastewaters, the groundwater levels also indicate uplift. However, the indiscriminate exploitation of groundwater and irregular and spot usage resulted in irregularities in changes in the trend of piezometers water levels. In addition to the survey of the groundwater chemistry data at 28 sampling sources with the most complete statistics and best dispersion total of 46 selective sampling sources located in this plain showed that during 2004 to 2014, the electrical conductivity is increased about 50 percent. The amount and percentage changes of hydrogeochemical parameters, the aquifer of old Shahryar plain can be divided into three sections including north, central and south. Comparison of the groundwater quality in these three sections indicates higher amounts and further increase of the major ions concentration and the level of electrical conductivity in the southern part of the aquifer and water quality degradation over time.