Abstract: A transmitting and receiving circuit was presented and developed for ultrasonic detection for tubes with small diameter and thin wall. Detecting for this kind of tubes usually encounters the difficulty of large curvature, small defects and small echo amplitude. The transmitting and receiving circuit is realized from two aspects. One is designing good transmitting circuit to excite the ultrasonic probe effectively. The other is designing good receiving circuit with low noise. The transmitting circuit can transmit high voltage pulse with the leading edge transition duration of 8 ns and the amplitude of -120 V. The range of the gain change of the receiving circuit can reach 80 dB. The experiments have been conducted by the transmitting and receiving circuit for detecting the titanium alloy tubes with different size. The minimum diameter and wall thickness of the tubes are 6 mm and 0.5 mm respectively. The artificial defects are fabricated in the tubes. The minimum defect is on the inner surface of the tube and the size is 0.05 mm(depth)×0.11 mm(width)×2.9 mm(length). The experiment results show that the transmitting and receiving circuit is well performed at the detection for the tubes with small diameter and thin wall.