The basic principle and chief features of ultrasonic phased array imaging inspecting technology are summarized. Using ultrasonic phased arrays, the defects of welds and Ti-alloy bars were realized. A phased-array transducer is composed of multiple elements. By precisely controlling the delays between the probe elements, ultrasonic wave beams of various angles, focal distances and focal spot sizes can be produced. The ultrasonic phased array technology can detect kinds of defects in workpieces quickly and ea...