As a wide-band gap (Eg=4.8 eV) semiconductor, the phase stability and lattice dynamics about the Ga2O3 under high pressure provide us the valuable information for its applications. However, the lack of the study on the phase stability and the lattice dynamics of Ga2O3 under high pressure makes the phase transition point remains controversial. In this work, we find that the irreversible β→α phase transition occurs at 20.1-22.7 GPa by using the high-pressure Raman scattering based on diamond anvil cell (DAC). We also provide the Grüneisen parameter and pressure coefficient of α-Ga2O3 and β-Ga2O3. Our results also suggest that the pressure coefficient of β-Ga2O3 exhibits anharmonic properties.