Abstract: Propagation characteristics of longitudinal modes of bolt embedded in soils were studied.The attenuation of longitudinal mode L(0,1) at a range of frequency from 40 kHz to 90 kHz was the smallest in all modes.Its energy velocity was the fastest.And its profile of displacement was simple,which made it to be excited easily.It was indicated that longitudinal mode L(0,1) could be used in the inspection of bolt embedded in soil because it could propagate longer distance in the bolt and be distinguished from other modes with slow energy velocity.At the same time,the experiments with bolts 22 mm in diameter,2 m in length embedded in soils detected using ultrasonic guided waves were carried out.It was shown that longitudinal mode L(0,1) between 40 kHz and 90 kHz was suitable for the inspection of length and construction quality of bolt embedded in soils.