<p>Understanding the hydrochemical characteristics of groundwater and their spatiotemporal evolution patterns is crucial for sustainable water resource management. This study focuses on the Handan-Xingtai region in China, analyzing the hydrochemical composition and spatiotemporal variation patterns of a total of 82 groundwater samples collected in 2018 and 2021. Self-Organizing Maps (SOM) were employed, combined with Piper diagrams, Gibbs plots, ion ratio analysis, and Pearson correlation analysis, to identify groundwater chemical types and their controlling mechanisms. Results indicate that the predominant water chemistry types in the study area are Ca(Mg)-SO₄(Cl) and Ca(Mg)-HCO₃, with localized occurrences of Na-Cl and mixed-type waters. SOM clustering grouped samples into four categories (C1: 68.29%, C2: 14.63%, C3: 15.85%, C4: 1.22%) dominated by Ca(Mg)-HCO₃, Ca(Mg)-SO₄(Cl), Na(K)-SO₄(Cl), and mixed types, reflecting the combined effects of carbonate dissolution, silicate weathering, and evaporative concentration. Ion ratios and Gibbs diagrams reveal groundwater chemistry is primarily governed by carbonate dissolution and cation exchange, with significant local influences from evaporation and human activities such as mining and fertilization. Correlation analysis indicates extremely significant positive correlations between TDS and Na⁺, Mg²⁺, Cl⁻, and SO₄²⁻ (with correlation coefficients r ranging from 0.86 to 0.95), confirming evaporation-concentration and salt dissolution as primary controlling processes. Weaker relationships between NO₃⁻ and other ions suggest its main sources are agricultural activities and domestic discharges. This study identifies the controlling factors influencing groundwater chemistry evolution in the Handan-Xingtai region, providing a theoretical basis for groundwater resource protection and rational utilization.</p>