Abstract: According to the characteristics of austenitic stainless steel welds and the relevant standards of phased array ultrasonic testing for welds, generally longitudinal waves are used for testing inner and bottom areas of welds, and creeping waves are used for testing near-surface areas of welds. The adjacent beams in the groups overlap each other to ensure coverage of the entire weld area, resulting in multiple groups of testing images. With such group testing method, sometimes the same flaw may appear in the testing images of multiple groups, and the same flaw may be assessed multiple times with different locations and sizes in the assessment result in the case of direct image assessment. Specific to such problem, a PAUT (phased array ultrasonic testing) image fusion technology is proposed in this study by means of the fusion of testing images in each group, correction of flaw locations and normalization of testing sensitivity. The ultrasonic images after fusion will not show the same flaws, which avoids the same flaws being assessed multiple times and improves the efficiency and quality of image assessment.