Abstract: The effect of hole number and the diameter of holes of perforated pipe on the attenuation of torsional guided wave mode,T(0,1),at low frequency is investigated by finite element simulation and experiment.First,propagation characteristics of torsional guided waves at low frequency in free steel pipe are theoretically analyzed.Then,group velocities of T(0,1) mode at different frequencies are obtained by finite element simulation and experiment and compared with theoretical dispersion curve of this mode.Result show that finite element simulation is valid,and the excitability of T(0,1) mode by thickness shear mode transducers is effective.Based on this,the fittest excitation frequency for T(0,1) mode inspection of perforated pipe is confirmed to be 30 kHz.Finally,both finite element simulation and experimental results show that the signal amplitude of T(0,1) mode at 30 kHz decreases in different extents along with the increase of the hole number and the diameter of the hole.These results provide a foundation for nondestructive inspection of perforated pipes by using T(0,1) mode at low frequency.