Abstract: Longitudinal and circumferential grooves were processed on the smalldiameter tube gauge of 60mm×6mm, which was tested by using domestic guided wave transducer. The results show that the detectable distance is about half circumference on using circumferential guided wave to test longitudinal groove and about 250mm while using longitudinal guided wave to test circumferential groove. The detectable distance decreases rapidly with the decrease of the groove depth. Based on the test results, the test procedures were established for field testing and were actually implemented. The results show that the domestic guided wave transducer can detect the etch pit effectively.