Abstract: Ultrasonic guided waves have been widely used in oil and gas pipelines nondestructive evaluation due to its various corresponding advantages, such as single-point excitation, long detection range and 100% cross-sectional detectability. However, the existing ultrasonic guided waves detect technology only can locate the defects in the axis position along the pipe by A-scan signal, and the application effectiveness is not good in large diameter pipes and some specific parts, such as pipe bracket and unequal-diameter three-way piece. This article compares the application characteristic of circumferential scan technology with existing detect technology by modeling and simulation, and has found that the circumferential scan technology is more suitable for middle range of large diameter pipe. Then numerical evaluations and experiments indicate that the defects both in axial and circumferential direction can be located by B-scan imaging by using circumferential scan technology, and the backscattering amplitude of defects is three times larger than that by existing T(0,1) mode detected.