Abstract: The outer square inter round stainless steel pipe was tested by ultrasonic wave. The result indicated that completing the ultrasonic test for whole volume in higher sensitivity using liquid immersion method of multiple probes, could detect all equivalent flaws of  0.5 mm×4 mm and R 0.5 mm×2 mm semicircle notches in longitudinal and converse direction in the outer square inter round stainless steel pipe.