Abstract: For understanding the microscopic interactions of electrolytes in mixed aqueous environments, this study systematically investigated the crystallization thermodynamics of anhydrous magnesium sulfate （MgSO₄） in a water-ethylene glycol （H₂O/EG） binary solvent system. The solubility, supersolubility, and metastable zone width （MSZW） were determined using the dynamic laser method across varying temperatures （303.15−333.15 K） and solvent compositions （H₂O∶EG molar ratios ranging from 9∶1 to 1∶9）. Key findings revealed that MgSO₄ solubility increases with temperature but decreases with rising EG content. Adsorption of EG on crystal surfaces creates steric hindrance, significantly broadening the metastable zone. Among five evaluated thermodynamic models （Apelblat, Van’t Hoff, Redlich-Kister, polynomial, Jouyban-Acree-Van’t Hoff）, the polynomial model exhibited optimal correlation （R²>0.99）, while the Jouyban-Acree-Van’t Hoff （JAVH） model enabled precise full-condition prediction. Thermodynamic analysis confirms an endothermic process （Δ_disH⁰>0） dominated by enthalpy changes and non-spontaneous dissolution （Δ_disG⁰>0）. A surface entropy factor （f >5） indicated a spiral growth mechanism, consistent with the decreasing interfacial tension （γ） trend at lower temperatures. Density and apparent molar volume data confirmed weakened solute-solvent interactions at elevated temperatures. Agitation narrows the metastable zone by enhancing mass transfer, whereas rapid cooling broadens it due to localized supersaturation. The 3D classical nucleation model demonstrated superior accuracy in predicting MSZW. These findings deepen fundamental insights into MgSO₄ behavior in mixed solvents and provide critical data for optimizing industrial crystallization processes and designing functional materials.