Abstract: In this paper,we presented a method of design and implement of an automatic ultrasonic inspection system HAUT-l for with flaw with four channels. The configuration of HAUT-l includes magnetic wheel, ultrasonic scanner,water couplant pump,motor controller, ultrasonic transmitter and receiver, high-speed data collection circuition welding tracing device and portable industrial computer. HAUT-1 can be applied to inspect the flaws of 10~1 00 mm-depth armor plate,huge sphere tank and conduit pipe. Moreover, the performance of HAUT-l,the method of automatic inspection and the algorithm of tracking weld were analysed and discussed further. And experimentation on welding φ1 600-specimen and φ1 800-boiler drum showed that HAUT-l has eximious performance in the precision of inspection,the reproducibility and the image manipulation of the flaw.