Abstract: Two imaging modes of sectorial scanning in ultrasonic phased array inspection are described respectively based on actual geometric structure and sound path in this paper. The near surface cracking defects are detected by phased array sectorial scanning and imaged via the two above-mentioned modes. The imaging mode based on actual geometric structure is found better than the other after comparing the imaging results. It is easier to accurately interpret the images displayed by the imaging mode using actual geometric structure,which will benefit the improvement of inspection efficiency and welding quality control.