介绍了NDT超声波探伤仪的工作原理，阐述了高速重轨在线探伤前的各项准备工作：样轨的制作、探伤仪灵敏度的调整、以及标样的重复性报准试验，并对超声波探伤仪在高速重轨中的应用进行了大量试验，经统计、对比、化验和分析，得出如下结论：超声波探伤仪整体性能稳定、可靠;高速重轨检出率低于其他重轨检出率;检测中尚未发现漏检，但存在部分误检现象;检出伤轨中，绝大部分缺陷集中在轨腰区域，这些缺陷主要是氧化物，硫化物和硅酸盐夹杂。

This paper introduces the work theory of NDT ultrasonic flaw detection instruments and details all kinds of preparing items: manufacture of sample rail, sensibility adjustment of ultrasonic instruments and exacted repetitive test of standard sample rail. This paper makes a lot of application experiments of NDT in the high speed rail ultrasonic flaw detection. Following conclusions were drawn through stating, contrasting, assaying and analyzing: the whole capability of NDT is stably and credible; and the inspection rate of high speed rail is lower than other rails. Although the phenomenon of undetected fault during inspection is not found, there are still a few miscalculations, many of which are centralized in the middle of checked rail due to oxidation, sulphuration and silication.