The equations of which the seismic waves are propagated in the viscoelastic medium have been built by imitating the viscosity properties of the earth with several ordinary viscoelastic bodies in this paper. The solutions of the problem have been obtained based on the proper approximate methods. It is given that the concept and the method which is used to estimate the viscocity Q value according to correct other factors causing the seismic waves energy decrease with Chebyshev polynomial approximate to power spectrum. At the end of this paper, the feasibility of the method has been is discussed.