Abstract: The double ellipsoidal heat source model combined with the phase field model was used to simulate the temperature field and the growth behavior of the intermetallic compounds （IMC） in the process of aluminum/steel dissimilar metal welding.The IMCs are composed of Fe₂Al₅ and FeAl₃,and Fe₂Al₅ occupies the main part of the IMC layer.The results show that Fe₂Al₅ is formed at first,then a small amount of Fe atoms combine with Al atoms to form FeAl₃.Solute segregation is formed between the dendrites of Fe₂Al₅ due to a large amount of solute aggregation,which leads to the reduction of mechanical properties of the welded joint.The dendrite arm spacing and thickness of Fe₂Al₅ decrease with the decrease of welding current,which can effectively improve the mechanical properties of the aluminum/steel welded joint.