Abstract: Abstract: Ultrasonic TOFD technique was used to detect the pipe for specification of  80 mm×19 mm. Regulation means of instrument parameters were explained for the wedge block after grinding and sensitivity comparison test was operated on the same thickness steel plate. The experimental result showed that the defect could be detected effectively after the wedge block being worn to the curvature as the pipe to be tested. Compared to the same thickness steel plate, no obvious change was observed for the test sensitivity.