Abstract: In this paper, gas metal arc welding tests were carried out on dissimilar metals of T2 copper and 304 stainless steel using HS201 solid wire, Cu-Si flux-cored wire and Cu-Ni flux-cored wire. This paper mainly studied the effects of alloy elements (Si, Ni) on the connection mechanism, microstructure and mechanical properties of T2 copper/304 stainless steel welded joints. The results show the welds formed by 3 groups of welding wire are good, and there are no macroscopic defects in the cross section of the welded joint. The obvious transition regions is found at the interface between the steel base material and the weld of HS201 and Cu-Si welded joints, and the microstructure can be divided into iron-rich phase and copper-rich phase. There is no obvious transition region in the Cu-Ni joint, and there are more iron-rich phases in the weld, mostly in the form of dendrite. The Si and Ni elements can significantly improve the impact toughness of the weld, and the impact absorbing energy of Cu-Ni weld is the highest (A_KV=54 J), which can reach more than 83% of the copper base metal. In the weld zone of Cu-Ni welded joint, the area with high hardness value accounts for the largest proportion, followed by Cu-Si welded joint.