Abstract: During the ultrasonic testing of the butt joint of Austenitic stainless steel, it is very important to fabricate the comparison test block with weld for the evaluation; and it is also effective method to adjust sensitivity for the system of probe and UT instrument. In order to make the block further meet the actual requirements, the specific block was designed and fabricated by the way of vertical welding, and compared with the block using flat and X-type groove, the block was regarded that it was more suitable to adjust the reference sensitivity. It was verified that the block satisfied the requirement in practice.