Plasma arc cutting sound has close relation with cutting conditions, so it contains useful information about this cutting process. In order to analyze the relationship between the plasma arc cutting acoustic signal and cut quality (including top and bottom kerf widths, bevel angle and dross attached level), a number of experiments under various cutting speeds have been carried out. It is shown that SPL (sound pressure level) of cutting acoustic signal shows mountain-shaped distribution with an increase of bottom kerf width. Experimental results also suggest the possibility to make an acoustic-based quality monitoring system for plasma arc cutting process.