Mercury is a metal with special physical and chemical properties. High pressure can significantly alter its crystal structures and interatomic interactions. However, vibration-related experimental data of mercury under high pressure have been scarce for a long time, which limits the in-depth understanding of its high-pressure phase transition mechanisms. To fill this research gap, this study systematically investigate the structural transformations and evolution of vibrational mode of mercury under high pressure. This was achieved by integrating low-wavenumber high-pressure confocal Raman spectroscopy, in-situ diamond anvil cell (DAC) techniques, and first-principles calculations. The study successfully detected the vibrational signals of two solid phases of mercury under high pressure for the first time, revealed the characteristics of pressure-dependent vibrational frequencies, and further calculated the relevant thermodynamic parameters of the two phases. The experimental data is highly consistent with the reported structural phase transitions of mercury, filling the long-standing experimental gap in this field and providing key experimental support for an in-depth understanding of the phase transition behaviors and related mechanisms of mercury under high pressure.