Abstract: This article introduces the methods of phased array and TOFD inspection and the differences between them.With referance to the features of ultrasound technology and the related standards as well as the experience in titanium alloy inspection with phased array technology,the feasibility of titanium alloy thickness plat weld inspection with TOFD technology is probed.The results show that with TOFD and phased array technology,localizable and quatitive detection for flaws of titanium alloy thickness plat weld can be conducted accurately and effectively.