Abstract: The ultrasonic inspection of reactor pressure vessel(RPV) safe end dissimilar metal welds is a challenging task because of the existence of cladding and austenitic coarse grain and complicated geometry of dissimilar metal welds. In order to improve the reliability and efficiency of ultrasonic inspection of safe end dissimilar metal welds, the conventional dual elements longitudinal wave(TRL) inspection technology and phased array(PA) inspection technology has been investigated in this paper. The results of examination indicated that TRL and PA inspection technology could detect the defects of dissimilar metal welds effectively, and the precision of defects sizing met the requirements of related rules. Hence, TRL inspection technology has been applied to the pre-service and in-service inspection of nuclear power plant; the accuracy of defect sizing and efficiency of PA inspection technology was better than that of TRL inspection technology.