Abstract: In this article, the construction structure, inspection theory and performing scheme of ultrasonic automatic flaw detection control device, and its application in oil and gas pipeline submerged arc welded steel pipe industry are introduced. It uses design of modular and modulation structures, thus ensuring the stable extraction of the control signal and the echo signal, and maintaining continuous automatic flaw detection accuracy and efficiency. So the developed device is characteristic of a high degree of automation, fast running speed, good compatibility and versatility, thus improving ultrasonic automatic flaw detection accuracy and reliability, and achieving misinformation rate of less than 2%, fail to report rate near to 0. Relevant operation shows that it can meet the requirements of oil and gas pipeline submerged arc welded steel pipe automatic ultrasonic flaw detection of production requirements.