Abstract: That seismic wave propagation is itself affected by small scale inhomogeneities of geologic bodies is an important issue of interpreting geophysical images and receives much attention in recent years. In this work, first of all, a statistical representation is used to describe small-scale inhomogeneities in seismological studies and a new way to build random media in which the preferred orientation of the small-scale inhomogeneities is expanded is proposed. Then, the importance of dealing with the errors is stated. And the long-wavelength theory of seismic wave propagating in horizontal layered media is discussed and its significance is pointed out. Next, based on 1D random layered media, the long-wavelength theory is studied by the local anisotropy factors' curves, and the influences of fluctuations in density and Poisson's ratio on the curves' pattern are analyzed. Finally, the characteristics of seismographic records of the 1D and 2D random media are studied especially when the long-wavelength theory can not be satisfied. For comparative analysis, we also compute the theoretical traveltimes of the equivalent media which is got by the long-wavelength theory when the 1D random layered media has different averaging lengths (The predicted traveltimes are got under the hypothesis that the anisotropy is weak), and then give some conclusions with guidance meanings.