Abstract: The propagation characteristics of L(0, 2) mode in curved pipes are investigated theoretically and experimentally for the purpose of defect detection in curved pipes by using ultrasonic guided wave. With experiments, transmission coefficients of L(0, 2) mode in 90?curved pipes with different curvature radii are tested.Resultsshow that mode conversion phenomena happen and their amplitude attenuates consequently when L(0, 2) mode propagates in curved pipes, and propagation distance and capability of defect detection are effected. Furthermore, transmission coefficients of L(0, 2) mode decrease while curvature radii increase. When excitation frequencies increase in the same curved pipe, transmission coefficients decrease.