Abstract: The software design of pipe ultrasonic automatic flaw detection system, and its application on welded steel pipes production were introduced. It combined traditional ultrasonic inspection technology with some advanced technologies, such as industrial control computer, virtual instrument, intelligent flaw detection, etc. With the careful programming flaw detection operation, it could evaluate correctly and select strictly for complex flaw echo, its error in alarm could be effectively avoided. The review of flaw echo waveform overcame insufficiency of flaw category identification in ultrasonic automatic inspection, and achieved misinformation rate being smaller than 2%, and fail to report rate being zero.