By the piezoelectric transducer hydrophone, laser-induced plasma sound waves in liquids were measured through experiments. Wavelet transform was applied to analyze the spectra characteristics of these signals acquired at different laser energy,different metal solid boundary and different laser wavelength.The results show that laser-induced plasma sound waves frequency range is 0~150 kHz,and changes of the laser energy, the metalboundary underwater and the laser wavelength have little effect on distribution of frequency of waves.Most energy of plasma sound waves is concentrated at the a6 level,and the proportion of the whole energy decreases with the increase of ionization energy of metal.The main frequency of sound waves is within 0~10 kHz,and the frequency peak is 5 kHz.