Abstract: The rock mass and joints are assumed as viscoelastic media to establish the propagation model of harmonic wave across viscoelastic joint. The transmission and reflection coefficient of harmonic wave across viscoelastic joint and waveform change rule of wavelet through joint are analyzed. The results indicate that viscoelastic joint has the low-pass filter property which leads to the decrease of the transmitted wave amplitude, the less prominent of the major lobe of waveform diagram of transmitted wave and the flatter of the waveform curve of transmitted wave after Ricker wavelet across viscoelastic joint; the phase change of wavelet propagation in viscoelastic joint can be described effectively by using correlation coefficient of waveform while the waveform change coefficient can reflect comprehensively the amplitude and phase change of wavelet, so the change rules are different when the wavelet waveform is analyzed by these two different coefficients; compared with shear stiffness and tangential viscosity coefficient, the normal stiffness and normal viscosity coefficient of the joints have greater effect on wavelet waveform change.