Abstract: In order to study the spatial distribution of groundwater in Huainan coalfield and the intensity of various hydrochemical actions, the coalfied is divided into the northern district with thicker loose beds and the southern district with thinner loose beds. Hydrochemical test data of main water-inrushing aquifers in 16 mines in these two areas were collected and statistically analyzed, ion combination method and Gibbs diagram were used to study the groundwater hydrochemical characteristics of each aquifer in north and south areas. The results indicate that TDS of aquifer is positively correlated with the burial thickness of unconsolidated formation. With the increase of the thickness of unconsolidated formation, the formation of hydrochemical components such as desulfurization, concentrated crystallization and cation alternating adsorption is enhanced, which makes SO₄^2- consume continuously to form HCO₃^-, resulting in the precipitation of HCO₃^- bound Ca²⁺, Mg²⁺, and finally the formation of highly mineralized groundwater dominated by Cl-Na.