Abstract: In this paper, the two typical defects of incomplete fusion and crack are studied by TFM (Total Focusing Method) technique. Firstly, the basic principle of TFM imaging technique is introduced theoretically. Secondly, the artificial flaw specimen containing the above defects are designed and fabricated, and the CIVA software is used to study the response of cracks and incomplete fusion. Then, the test of artificial flaw specimen is carried out, and the detection ability of conventional phased array technique and TFM technique for the above two defects is compared. Finally, conventional nondestructive testing is carried out on the specimen to determine the length of the flaws in the welds. The flaws of the specimen are dissected, and the burial depth of flaw and its own height can be measured. The results of detection and anatomy show that the TFM technique has higher detection resolution for the imaging of the above two flaws and less positioning and quantitative error, which can be applied to engineering practice.