Abstract: By using different exposure methods, the dissimilar metal weld testing samples with artificial defects(crack and the lack of fusion) were examined by radiographic examination, and the examination results for the defects were obtained. Through dissecting and measuring the defects sizing in testing samples, examination results and measuring value were compared. By using the analysis of detection/residual detection POD(a) & the signal response data POD(a), the reliability of the radiographic examination of dissimilar metal weld and the main influence factors of reliability of the radiographic examinations were evaluated. Finally, the detection probability and the detection probability curve were given.