<p>Hierarchical cluster analysis, principal component analysis, hydrochemical illustration, and objective weighting were used to study the hydrochemical characteristics and types of water–rock interaction of the groundwater in a typical North China Coalfield mine. The geological conditions and the mining disturbance were quantitatively evaluated, and mechanisms by which they affected hydrochemical evolution were elucidated. The results show that there are three types of groundwater in the coal measures: one with high Ca²⁺, Mg²⁺, and SO₄²⁻, which is oxidized disturbed water; another featuring high Na⁺ and HCO₃⁻, which is reduced disturbed water; and one with low ionic content, making it undisturbed water. The coefficients of geological complexity and mining disturbance intensity exhibited spatial variability, with maximum values of 0.46 and 0.8, respectively. Less oxidation of pyrite and less dissolution of carbonate and sulphate was correlated with increased geological complexity, while enhanced cation exchange and sulphate reduction correlated with decreased geological complexity.</p>