Abstract: The multi-physics coupling finite element software COMSOL was used to perform finite element analysis on the ultrasonic response characteristics of pressure vessel welds, and the effects of different probe parameters such as center distance, frequency, and angle on the test results were analyzed. The simulation results show that the simulation of sound propagation process is conducive to better understanding the defect characteristics and improving the assessment and identification of defects. The simulation of the probe parameters is conducive to the development of the inspection process. Properly reducing the center distance of the probe helps to separate the aliased through-wave and defect wave signals; appropriately reducing the probe angle can effectively improve the signal resolution; reasonably selecting the probe frequency is recommended and the basic principle is that a little higher frequency should be selected for thin-plate inspection and lower frequency should be selected for thicker boards.