Abstract: Described in the paper are the three commonly-used NDT methods and techniques for weld pipe flaw inspection,i.e.,the MFL detection,the eddy-current detection and the ultrasonic detection.Also analyzed are the advantages and disadvantages of these methods.The MFL method features high sensitivity which ensures satisfactory identification of both outer and inner flaws of the pipe,but in case of long large-sized heavy-wall pipe,demagnetization is necessary to be carried out upon ending of the detection.As for the eddy-current method,although the detection speed is rather high,it is so difficult to find out any flaw located deep in the workpiece due to the Kelvin skin effect.And speaking of the ultrasonic method,the advantages are high penetrating force,high flaw-positioning accuracy,low operation cost,and high detection velocity,but medium coupling is needed for the detection,which may cause,in winter,the trouble of freezing of the pipe,particularly in hilatitude areas,thus make it rather difficult to keep the detection operation going smoothly.