The end-corner reflection of ultrasonic and its characteristics are introduced。In steel-air interface, for example, longitudinal and transverse waves mode conversion and its effect on the time of echo signal transmitting are focused, in the process of the end-corner reflection. On the basis of the above, the causation of the variety of the end-corner reflection ratio and the selection of probe angle in practice are analyzed. Finally, the end-corner reflection identification method in ultrasonic testing of the weld is discussed.