Abstract：Wave equation in linear rheological medium is deduced in frequency domain, then approximate wave equation in the medium where viscoelastic parameters vary with location is also given in this paper. In addition, the relation between viscoelastic parameter and phase velocity or initial amplitude of each wave is shown definite1y. In an example, theoretical wave field in viscoelastic medium is obtained by using finite element method;then attenuation coefficients are derived from the initial amplitudes of its direct wave, transmitted wave and reflection wave; and finally the ratio of viscous parameter to elastic parameter is estimated by inversion. The comparison with model values says that the inversion values are reasonable and the method is reliable.
