Dispersion is the most remarkable feature of the channel wave. In view of this, this paper has deduced the dispersion function of the symmetrical three-layer model and drawn the dispersion curves. The characteristics of the dispersion curves are analyzed through theoretical calculation. The relationship between parameters of strata and characteristics of Rayleigh channel wave dispersion is also studied. It is indicated that the dispersion curve can be used to estimate the width or the velocity of the strata.