Abstract: TOFD technique, a non-destructive testing technology which has developed since the late seventies of the twentieth century, has already been widely applied in various industries such as pressure vessels and etc. Based on the “Announcement No.402, 2007” published by the Bureau of Special Equipment Safety Supervision in 2007, the application of the TOFD technique has gone through a rapid development in the pressure vessel industry. In August 31, 2009, TSG R0004—2009 “Supervision Regulation on Safety Technology for Stationary Pressure Vessel” clearly specified the TOFD technique, just like the radiographic testing, was also a feasible non-destructive testing technique for detecting the weld joint in the manufacturing process of pressure vessels. The TOFD technique now became the focus of the entire pressure vessel industry. This article briefly illustrated the basic principles of the TOFD technique and described its application and standard situation in China.