Human activities have seriously affected the quality of shallow groundwater in coal mining areas and understanding the spatial and temporal evolution of groundwater is a widespread concern. This study was conducted to determine the primary hydrogeochemical processes in the Sunan Mining region, China. We collected 84 groundwater samples from a Quaternary loose aquifer and tested the macronutrient content using standard methods. Multivariate statistical analysis and hydrochemical analysis were conducted to analyze the sources and formation mechanisms of groundwater constituents in the early, middle, and late stages of mining. Results show that the water quality evolved from Cl·SO₄-Na·Ca type to SO₄-Na·Ca type. Mineral dissolution, halite dissolution, cation exchange, and desulfurization primarily occurred in the groundwater, and the hydrogeochemistry was strong in the northern part of the study area; however, the degree of both dissolution and reaction gradually weakened with increasing mining activities.