Abstract: Finite element simulation was applied in multi-layer and multi-passes MIG welding of 19.05 mm thick Invar alloy to simulate the non-deformable models and the models with different anti-deformation angles. Then the Invar alloy multi-layer and multi-passes MIG welding experiments were carried out with the anti-deformation angle, which was designed according to the simulation results, besides, the deformation of the post welding specimen was analyzed. The result showed that the 2 degree anti-deformation angle could effectively control the post welding angular deformation of the four-layer and ten-passes MIG welding for 100 mm × 100 mm × 19.05 mm Invar alloy. The post-weld residual warpage height is −0.11 mm and the post-weld residual angular deformation is −0.12 degree. The error between the results and the simulation results was less than 8%. This conclusion proved that the finite element simulation technology had prediction and guidance for experiments.