In order to clarify the hydrochemical characteristics of groundwater in Gaohe Coal Mine, reveal the water quality status, formation mechanism and hydrogeological laws, and provide scientific support for the formulation of mine water prevention and control measures and the sustainable utilization of groundwater resources, this paper collected the groundwater samples of the Cenozoic loose aquifer, Permian sandstone fissure aquifer, Carboniferous Taiyuan Formation limestone aquifer and Ordovician Fengfeng Formation karst aquifer in the mine field. Combined with the hydrochemical indicators detection, statistical analysis and Piper three-line diagram visualization method, the core parameters and hydrochemical type characteristics of the main ion composition, total dissolved solids, total hardness, pH value of each aquifer were systematically studied. And the hydraulic connection of each aquifer was analyzed and its mechanism was clarified. The results showed that each aquifer had unique hydrochemical ' fingerprint ' characteristics. The hydrochemical type of the Quaternary loose layer was mainly HCO3-Ca·Na·Mg type, the Permian sandstone fissure water was mainly Cl-Na type and HCO3·Cl-Na type, the Taiyuan Formation limestone water was mainly HCO3-Na type, and the Ordovician Fengfeng Formation karst water was mainly HCO3·SO4-Ca·Mg type. The ion content in the vertical direction increased first and then decreased. Under normal geological conditions, the hydraulic connection between Taiyuan Formation and Ordovician aquifer was weak, and hydraulic connection possibly existed in structural development area.