Abstract: Considering the effect of constraint on deformation and residual stress, a finite element model of multi-layer and multi-pass welding of 616 armor steel thick plate structure was developed. The shape and size of the weld bead and residual stress were been calculated by using Sysweld software. The thermal cycles and deformation in multi-pass welding 616 armor steel with thick plate structure was simulate. These simulation results show good agreement with experiments. The results showed that the farer from fusion line, the peak temperature is lower and the time to the peak lag behind. The deformation occurred at the both sides of weld, arc starting and arc extinction position in which high stress exits.