Abstract: In this work, three imaging methods, such as ultrasonic phased array S-scan, multi-mode total focusing, and multi-mode fusion were used to reconstruct the slag inclusion defects in welds, and the authenticity of the multi-modal fusion image was verified by the notched test block. The results showed that the multi-mode fusion imaging could integrate the effective information of different modes and display the relatively complete three-dimensional contour of the defect, which was of great significance for the trend analysis and type identification of weld defects.