For the coupled reaction-extraction-alcohol precipitation process, it is necessary to investigate the effect of ethanol on MgCO3•3H2O at the molecular level. In this study, DFT calculations of the nesquehonite growth models were performed to analyze the growth unit adsorption mechanism in the presence of solvent molecules.Furthermore, molecular dynamics simulations of solid-liquid interface models and Mg(HCO3)2 solution boxes were conducted. The calculated results showed that with the ethanol effects, the adsorption rate of GU was increased by weakening competition of water molecules and the transformation rate of Mg(HCO3)2 to nesquehonite was raised by reducing the coordination number of magnesium ions.