Abstract: The austenitic stainless steel base metal is characteristic of coarse grains and its weld microstructure is columnar, which has strong scattering attenuation and distortion effect on ultrasonic wave. It is difficult to detect austenitic stainless steel effectively by using conventional ultrasonic testing technology, while phased array ultrasonic testing technology has the characteristics of high detection efficiency, high accuracy and real-time imaging, which provides a new way for the detection of austenitic stainless steel. The phased array ultrasonic testing technology was used to detect the pitting defects of austenitic stainless steel, and the feasibility of the technology was verified.