A numerical study was performed to identify the significant factors that influence numerical simulation of the spectral analysis of the surface waves (SASW) method. Damping, impulsive force magnitude, time step, element size of mesh, and soil layer profile were all parametrically studied. An axisymmetric finite difference code was adopted to simulate the surface wave propagation in layered media. The phase spectra method was utilized to obtain the dispersion curves and shear wave velocity profiles of the soil strata. The most important factor influencing the SASW numerical modeling is the shear wave velocity profile of the soil layers. The shear wave velocity of the soil layer also dominates the fluctuation of the cross power spectrum.