To study characteristics of acoustic wave generated by Q-switched laser on dermal pigmented lesions, pieces of derma peeled from a cavy's body are plucked their hair. The pieces of derma are radiated by Q-switched laser with different energy intensities. Momentary signals of acoustic wave generated by the Q-switched pulsed laser on dermal pieces are detected isochronously with sensors connected to a multi-channel digital oscilloscope. The signal data are analyzed with a personal computor. Clear signal curves of acoustic waves are obtained in the experiment. The amplitudes of the signals present the positive correlation with the energy intensity of the single pulse laser. The acoustic wave signals have practical meanings of reference to the real-time control of laser energy intensity in the course of the therapy of Q-switched laser on dermal pigmented lesions.