The study analyzed the hydrochemical characteristics of groundwater in over-exploited area of northern Wei Fang and elaborated the temporal and spatial variation of hardness and TDS. Meanwhile, it revealed the law of groundwater quality under the influence of over-exploitation in recent years. It is based on the hydrochemistry elements of shallow groundwater in the over-exploited areas by the comprehensive use of radial plot, box-whisker diagram and Piper diagram. The results showed that:①Hydrochemistry type in over-exploited area changed in the recent years. The chemical types of groundwater were mainly dominated by Na+—K+—HCO3- and Ca2+—Mg2+—HCO3- in 2000, and they were Na+—K+—HCO3-—Cl- ,Ca2+—Mg2+—HCO3-—Cl- in 2012. ②Excessive exploitation of groundwater changed the flow field of groundwater, increased the infiltration recharge and pollution of water, which resulted in the increase of total hardness and TDS concentration. ③From the view of interannual variation of the groundwater chemical composition：Na+, K+, Cl- and HCO3-were the same as groundwater level, and the ionic concentration changed with the fluctuation of groundwater level. Ca2+, Mg2+ and SO42- increased with decreasing groundwater level. Over-exploitation leads to increase dissolution of minerals containing calcium and magnesium and gypsum, thereby increasing the infiltration capacity and ion concentration.