Abstract: Analyzed in the essay are the main aspects of the automatic OCTG flaw ultrasonic detection system,covering the equipment configuration,detection principle,implementation plan and application result,etc.This UT system is designed with modular and modulation structures,being a digitized multi-channel system with a flexible channel combination from the minimum 1 to the maximum N.Together with the elaborate operation program,the automatic UT system is capable of providing such advantages as accurate evaluation and strict screening of complex flaw echoes which make any false alarm avoided,automatic discrimination of and alarming for defects,automatic defect information storage and playback of flaw echo waveforms,and higher inspection accuracy and reliability,i.e.,the erroneous evaluation rating:under 2%,and the undetected defect rating:0.