Abstract: The application of the phase inversion technique in tissue harmonic imaging is theoretically and experimentally studied in the paper.Based on the nonlinear propagation theory of the finite amplitude sound wave,it is proved that the fundamental frequency component is efficiently suppressed while the second harmonic component is doubled by the use of the phase inversion technique.Measurement of the axial and lateral beam profiles demonstrates that the fundamental frequency component is suppressed by about 30 dB to 50 dB while the second harmonic component is enhanced by 6 dB,which coincides well with the theoretical predication.Experimental system for tissue harmonic imaging with phase inversion technique is setup and images for several biological tissue specimens are obtained.Compared with the traditional fundamental frequency imaging and the second harmonic imaging,the second harmonic imaging with the phase inversion technique can improve the clarity and contrast of image.