Abstract: Because of welding technology, hot cracks are easily found in the austenitic stainless steel pipe weld, and these hot cracks characters are that they always have the short length, little through wall size and most of them always appear in the surface and near surface areas of the weld. Also, because of the reason of the austenitic stainless steel material, volume inspection techniques in accordance to code can not get a good result. This paper introduces the investigative ultrasonic techniques of hot cracks for austenitic stainless steel pipe weld, including the verification of the techniques and giving some reference to the inspection techniques of such hot cracks.