In this study, to discuss the effect of the boundary between pipeline and clamp support changed by different pressures to the propagation of guided wave in the pipeline is the main idea. In addition, the author simulates the wave propagation situation by using finite element method. In this work, T(0,1) torsional mode was used to discuss when adding different pressures to the clamp support, the change of its reflection coefficients in different frequencies by the axial symmetric property propagates in the cylinder pipe. In the simulation, we take the ¡§fictitious layer¡¨ was used to describe the situation between the clamp support and pipeline when adding different pressures. Moreover, the stiffness normal to the fictitious layer and the stiffness parallel to the fictitious layer were taken as material parameters to achieve the situation between clamp support and pipeline. According to experimental results, when the torque increases, the reflection coefficients will decrease with increasing frequency. The reflection coefficients are about 0.08 to 0.02. By the result of experiment and simulation, one can know that when adding torque on the clamp support increases, the reflection coefficient will decrease. In addition, the author also prove that if we change the stiffness parallel to the fictitious layer material factor, then the T(0,1) guided wave will be more sensitive by its action of particle motion.