Abstract: In this article, based on the analysis of ultrasonic testing of welding joint in the current standard and on the relative criteria, and in the combination of considering the corresponding probabilities of the longitudinal and transverse defects appearing in welded joint in the process of welding, the authors put forward the ways for effectively detecting the transverse defects in the joint with no undetected ones in view of actual demand and operability of the methodology, which may give some modifications for related standards.