Abstract: With the weld quality detection technology developing rapidly, combined with the actual working conditions, the test results of new technologies and equipment are worthy of further analysis. By the studies of large number of TOFD test cases, several common pseudo-defect maps were found, which was very easily leading to the false alarms. After the analysis of working conditions, structural stress, as well as on-site materials used, in combination with other detection methods and actual anatomic validation on comparative analysis of the spectra characteristics, the cause of false report and how to prevent it was found out.