研究采用超声导波对在役管线腐蚀缺陷等进行大范围在线无损检测。选择可远距离传播、对内外表面及圆周方向的缺陷具有同样灵敏度的导波模式；采用脉冲激光光纤阵列激励导波，压电传感器阵列接收导波信号；研究管线内外表面缺陷对导波传播的影响及波型转换问题；用现代信号分析技术反演缺陷的位置及大小，为管道的运行、检测、维修、更换提供依据。

Based on the elastic wave propagating theory, we researched the propagation characteristics of guided wave in a plate, bar or pipe. To get disperse.curves and displacement distribution charts of different guided modes along pipe wall thickness; a special computational software was developed. It could be used to achieve the numerical simulation of the propagation of guided wave in some structures. We also built an experimental set-up , which was used to excite or receive guided wave. In this system, an arbitrary waveform generator for exciting ultrasonic guided waves was made. We researched and developed a.length-expander type of piezoelectric array transducer and exciting-receiving.signal switch by ourselves. Using this experimental system, we excited some.special guided modes in the plate, bar or pipe. By analyzing the characteristics of different modes, a criterion of choosing right testing mode was presented by us. Finally, we used special guided modes to detect some artificial defects on the plate, bar and pipe. The experimental results were good with the theoretic forecast.successfully. All the results showed that it is feasible to apply guided wave for long-range non-destructive test (NDT) of pipe.