Abstract: Propagation of guided waves in bended pipes is more complicated than that in straight pipes because of the complex geometry of bends. The transmission coefficient is an important factor used to evaluate the accuracy of the test. In this study, the finite-element method (FEM) is used to investigate the influences of the angle of bends, the radius of bends and the excitation frequencies on the transmission coefficients of T(0,1) guided waves. Our results show that the transmission coefficients varied with the excitation frequencies of guided waves when propagating through a bend. Given that the frequency of guided wave is high enough, new wave fronts are more easily produced after the guided wave propagating through a bend. It is also found that when guided waves propagating through a bend with the minimal transmission coefficient, their frequencies are correlated with the angle and the radius of the bend. The transmission coefficients oscillate periodically with increasing angle of the bend. The correlation between transmission coefficients and frequencies of the guided waves is verified by experimental data. In conclusion, it is suggested that guided waves propagating at various frequencies should be used to test bended pipes.