The invention discloses a guitar supersonic tone-improving machine. A lifting press head is fixed on a guitar fixing bench, and a supersonic vibrator is disposed under the lifting press head. The supersonic vibrator is connected with the output end of a supersonic wave generator, and presses a guitar panel. A working method of the tone-improving machine comprises the steps that the supersonic vibrator presses the guitar panel, and enables the supersonic energy from the supersonic wave generator to be converted into mechanical vibration; the pressure of a string is simulated for a bridge part of the panel; and then the intensified mechanical vibration of the panel is performed, thereby improving the stress distribution of the panel, improving the tone of the generated sound of the panel, and achieving the improvement of the tone of the guitar. The tone-improving machine employs the supersonic fine massage, i.e., internal massage, for massaging a sound generation plate unit, can effectively eliminate the internal stress, improves the material structure, can greatly reduce the manual tone improving time, and improves the tone of generated sound of the guitar panel more quickly. Duringtone improving, an operator cannot hear noise, so it is very quiet.