The bend pipeline is a common form of piping in the pipeline industry, and the elbow section is the weakest part of the entire bend. Due to bending stress and material erosion, various defects can easily occur. Ultrasonic guided waves can effectively detect defects in pipeline structures, and numerous studies have validated and advanced the application of this technology in straight pipe inspections. When ultrasonic-guided waves pass through the elbow of a bend, they undergo complex changes, which can affect the defect detection performance of the guided waves in the pipeline. To address this issue, the finite element method is used to quantitatively study the propagation characteristics of the longitudinal L(0,2) mode-guided waves in the elbow region and the straight pipe section after the elbow through full-wavefield simulation data. The study analyzes and discusses the influence of the elbow structure on the guided wave propagation, wavefield distribution, and interaction with defects, as well as the detection of defects at different positions in the bend. The findings are evaluated through experiments. The results show that the elbow structure in a bend causes significant attenuation of ultrasonic-guided wave energy, and the distribution of the guided wave field changes in both the axial and circumferential directions, showing different energy focusing and diffusion characteristics before and after the bending point of the elbow. The propagation characteristics of ultrasonicguided waves in the elbow of a bend are closely related to the axial position of wave arrival, the bending radius of the elbow, and the excitation frequency. The guided waves after the elbow introduce asymmetric modes, presenting additional complexities. This research contributes to a deep understanding of the propagation characteristics of ultrasonic-guided waves in bends and provides a theoretical foundation for further utilizing ultrasonic-guided waves to achieve comprehensive defect detection in bends.