Abstract: It is imminent to improve the reliability of thick-walled pipe inspection in power plant boiler, as the conventional ultrasonic testing has many disadvantages, such as large blind spots existing near the surface and test results being affected by human factors. With the advantage of the high defect inspection ratio and high reliability, the ultrasonic phased array inspection technology was described and the test process was analyzed in the text. At the same time, the application of the ultrasonic phased array inspection technology in power plant boiler thick-wall pipe testing was illustrated.