Abstract: Based on the thermal elastic-plastic method, the dynamic stress-strain deformation process of AH36 steel welded joint with 160° butt joint was studied. At the same time, the sample was made, and the dynamic change of welding strain was recorded by three-dimensional full-field strain measurement and analysis system, which verified the accuracy of welding finite element results. The effects of preheating temperature and welding velocity on dynamic stress and strain were analyzed. The results show that with the increase of preheating temperature, the welding deformation decreases gradually. When the preheating temperature is 200 ℃, the average welding deformation is reduced by 34.6% compared with the average welding deformation without preheating. At the same time, the distribution of welding stress field is improved, and the compressive stress distribution area of weld and heat affected zone is increased, but the stress amplitude is not sensitive to the change of preheating temperature. The welding deformation increases with the increase of welding velocity. When the welding velocity is greater than 5 mm/s, the growth trend gradually slows down, and the equipotential distribution area of the welding deformation field decreases. With the increase of welding velocity, the distribution area of welding compressive stress field decreases, and the distribution area of welding tensile stress field increases. The change of welding velocity will also cause the stress of middle layer thickness to fluctuate.