Based on the Biot’s wave theory and thermoelastic theory for saturated porous medium, three relaxation factors were introduced and the generalized thermoelastic theory for saturated porous medium was developed. Reflection of SV waves on the surface of the plane was used to analyze the influence of relaxation effect on the reflection, and the expressions of the reflection coefficient for the p₁ wave, p₂ wave, T-wave and S-wave were derived. Numerical results were obtained and used to discuss the difference of reflection amplitude for four kinds of reflection waves among the generalized thermoelastic theory G-TE, L-S theory, and G-L theory. The effect of the relaxation time factors was also discussed. It is indicated that there is apparent effect of G-TE, L-S theory, and G-L theory on the results and it is different from p₁ wave,p₂ wave and S-wave. In addition, there is greater effect of relaxation time on p₂ wave, and less effect on p₁ wave, and the effect can be omitted on the S wave.