The aim of this paper is to present the simulation and experiment of the welding butt-joint aluminum alloys to low carbon steel using Visual-weld software and the metal inert gas (MIG) welding process. The workpiece is set up in a virtual environment with an area of 150 x 70 x 5 mm, a welding speed at 3.5 mm/s, and a heating source of 2.5 kW. The finite element method (FEM) is used as a powerful tool in simulating, calculating and predicting the welding stress and distortion at the early stage of the design process and development of welding products. The metallurgical process, deformation, hardness, etc. are investigated using the FEM in Sysweld software. The microstructure of the intermetallic layer is observed using scanning electron microscopy. The hardness of the intermetallic layer is examined using Vickers hardness testing. Tensile strength and bending strength are examined by tensile and compress multimeter equipment. To improve the quality of the aluminum/steel welds, the IMCs layer should be as small as possible. The experimental results are better if the welding current of range of 95 – 100 A and the welding speed is from 3.5 to 4 mm/s.