As the main water supply source in Zhangjiakou area, the water quality of groundwater has deteriorated in recent years due to human activities, which has affected the local water safety. It is of great significance to find out the chemical characteristics and water quality of groundwater for rational utilization of water resources. Based on the water quality data of 2020, Ca^{2 +}, Mg²⁺, K⁺, Na ⁺, HCO_3-, TH, pH, TDS, , Cl^-, Al³⁺, NO₃^-, F^-, Cr⁶⁺ were selected as water quality factors. The hydro-chemical characteristics of shallow groundwater in the Chaixuan Basin of Zhangjiakou were analyzed by mathematical statistics, Piper diagram, Gibbs diagram and endmember diagram of rock weathering. The groundwater quality was evaluated by fuzzy comprehensive assessment and improved Nemerow index method. The results show that the groundwater in the study area is weakly alkaline freshwater dominated by Ca²⁺ and HCO₃^-, of which micro-hard water, hard water and hardest water account for 39.51%, 34.57% and 25.93%, respectively. The hydro-chemical types change from HCO₃-Ca·Mg, HCO₃-Na, SO₄·Cl-Na to HCO₃-Ca·Mg, HCO₃-Na, SO₄·Cl-Ca·Mg along the groundwater flow direction. The spatial distribution characteristics of hydro-chemical components are mainly affected by the weathering and dissolution of silicate and carbonate and human activities. The groundwater quality meets the standard of Class III on the whole, but the groundwater quality in some areas is poor. Along the flow direction of groundwater, the water quality gradually deteriorates, which is mainly affected by the primary geological environment and industrial and agricultural pollution.