Abstract: By using first-principles calculation methods, the unit cell structure of Mg₂Ca, Al₂Ca and Mg₂Si phases under hydrostatic pressure of 0-50 GPa was optimized.The elastic properties and electronic structure of Mg₂Ca, Al₂Ca and Mg₂Si phases under different hydrostatic pressures were calculated.The influence of hydrostatic pressure on the stability of each phase structure, elastic properties and electronic structure were studied.The results show that the lattice constants of Mg₂Ca, Al₂Ca and Mg₂Si phases gradually decrease with the increase of applied pressure, and the rates of decrease show a gradually slow trend.After the hydrostatic pressure is gradually applied, the bulk modulus, shear modulus, Young's modulus, Poisson's ratio and bulk modulus/shear modulus of Mg₂Ca, Al₂Ca and Mg₂Si phases all show different degrees of growth.It shows that applying proper hydrostatic pressure can increase the plasticity and ductility of Mg₂Ca, Al₂Ca and Mg₂Si phases, thereby improving the mechanical properties of magnesium alloys.With the increase in pressure, the structure of each phase does not change, and the structure of Mg₂Si shows the strongest stability under hydrostatic pressure, followed by Al₂Ca, and the stability of Mg₂Ca gradually deteriorates under hydrostatic pressure.