To investigate the dispersive character of cylindrical Rayleigh wave, a finite element model is developed to simulate laser inducing cylindrical Rayleigh waves on the surface of an isotropic cylinder. This model is based on the thermoelastic mechanism and can take the temperature dependence of material properties into account. Verifying the correctness of the model, the waveforms of cylindrical Rayleigh waves induced by laser on the cylinders with different radii was calculated, and quantitatively analyzed the influence of the cylinder′s diameter on the dispersion character of cylindrical Rayleigh waves by the phase spectral analysis method. The results show that with the frequency increasing, the phase velocity of cylindrical Rayleigh wave rapidly increases to the maximum value CRmax, and then gradually decreases to that of plane Rayleigh wave CPR. Moreover, as the radius of cylinder increases, the dispersion of cylindrical Rayleigh decreases, until the radius increases to ∞ (plane), the dispersion will vanish.