Abstract: The outer surface of fillet welding seam of pipe seat is a curved surface relative to branch pipe. The surface structure of fillet weld will produce reflection signal in phased array pattern, and its position is constantly changing, which seriously affects the evaluation of defects. Based on the analysis of the influencing factors of defect location, an appropriate method is proposed to correct the defect location, which effectively eliminates the interference of structural reflection signal and improves the accuracy of defect detection.