Abstract: Surface hydration properties of minerals play a critical role in flotation. This study employed Materials Studio integrated with density functional theory and molecular dynamics simulations to construct optimized crystal models of magnesite/dolomite and collector CP molecules. Systematic analyses of frontier orbital energies, wettability behaviors, and interfacial interaction energies revealed: Frontier orbital analysis demonstrates a smaller energy gap between CP and magnesite (2.643 eV) versus the dolomite system (2.670 eV), indicating preferential electron transfer from CP's HOMO to magnesite's LUMO orbital. Wettability simulations show dolomite exhibits a lower contact angle (7.5°) than magnesite (9.2°), confirming its stronger intrinsic hydrophilicity. Post-CP adsorption, water diffusion coefficients on magnesite surfaces exceed those on dolomite, significantly enhancing hydrophobicity. Interaction energy analysis verifies CP exhibits superior adsorption energy (-406.8 kJ/mol) and deformation energy (166.7 kJ/mol) on magnesite compared to dolomite (-95.6 kJ/mol and 161.9 kJ/mol, respectively). This work elucidates the molecular-scale selective mechanism of CP towards magnesite, establishing a theoretical framework for hydration regulation and flotation separation of Ca-Mg carbonate minerals.