Abstract: The propagation of ultrasonic guided wave in elbow pipe is more complex than that in straight pipe. However, the detection of elbow pipe part is especially important in the actual engineering site. The torsion mode T(0,1) excited by magnetostrictive ultrasonic guided wave was used to study the problems of ultrasonic guided wave in the detection of defects in typical parts of the bend and the influence of different detection frequencies on the detection of defects in the bend. The results show that the low detection frequency makes it difficult to separate the ultrasonic guided wave reflection signal at the defects of the dorsal side of the arch and the elbow weld due to the frequency dispersion. When the detection frequency is high, the amplitude of the defects on the inside of the arch back and the outside of the arch back is small. Therefore, selecting appropriate detection frequency can effectively identify the elbow defects. When the mode T(0,1) wave passes through the elbow, the energy focuses on the outside of the arch dorsum and diverges on the inside of the arch dorsum. Therefore, it is relatively easy to detect the defects on the outside of the arch dorsum as compared with those on the inside, which are easy to be undetected. After the signal through the elbow, the energy attenuation is serious, about half of the original energy.