Abstract: The grains in arc additive manufacturing metal are uneven and distributed in laminated form.In order to explore the influence of the characteristics on the ultrasonic propagation, the multi-layer muti-pass arc additive manufacturing metal sample was prepared, and the grain size and distribution of the sample in each region were obtained by using metallographic analysis.Overall modeling method for laminated polycrystalline structure was proposed based on the grain size and grain orientation distribution, and the finite element simulation model of laser ultrasound in arc increasing material was established.The laser ultrasonic testing experiment was carried out, and the actual laser ultrasonic longitudinal wave signal was obtained.The simulation results were consistent with the experimental results.This study provides theory and method guidance for modeling laminated anisotropic polycrystalline materials and revealing the law of ultrasonic propagation in arc additive manufacturing materials.