Thermodynamics and dynamics of Mg3Zn6Y quasicrystals in solidification process were detailedly studied in this paper. The free energy, nucleation rate and nucleation energy were deduced and calculated. It shows that the driving force and nucleation rate gradually increase with the decreased temperature. The further studies show that the nucleation energy increase gradually with the decreased liquidus temperature. And it is apt to quasicrystal nucleation by increasing the cooling rate in a proper temperature range.