ABSTRACT In the detection of pipeline defects hidden after the support structure, the energy cannot be effectively transmitted to the defect and reflected to the transducer due to the existence of the support structure, resulting in the missing detection of defects. Torsional mode guided wave has certain advantages in defect detection of support pipelines because of its non-dispersive feature. Hence, a detection method with the torsional mode guided wave of multi-element axial local excitation is proposed to solve the problem. Firstly, the influence of different connection mode, element number, and element spacing on the transducer performance is discussed in detail by both simulations and experiments. Secondly, the performance of the transducer for detecting defects hidden after the support structure is verified by both simulations and experiments. The results show that when the number of elements is 3, the elements spacing is 3 mm, and the connection mode is parallel exciting and series receiving, the amplitude of the defect echo is 2.7 times that of the traditional ultrasonic guided wave detection method. In addition, the designed transducer could detect 3 mm diameter through-hole defect hidden after the support structures.