Abstract: The Fe Co Ni Cr Cu_0.5high entropy alloy was welded with 304L stainless steel by resistance spot welding technology, and the surface morphology of welding spots was observed by means of surface 3D contour measuring instrument,optical microscope （OM） and scanning electron microscope （SEM）, and the element diffusion, precipitation behavior and welding defects between high entropy alloy and 304 stainless steel were analyzed. The results show that Fe Co Ni Cr Cu_0.5high-entropy alloy can be successfully welded with 304L stainless steel by resistance spot welding, but there are some cracks and empty holes in the melt zone and the heat affected zone after welding. These cracks can be summarized as crystallization cracks in the melt zone and liquefaction cracks in the heat affected zone. Due to excessive welding current and long welding time, the molten liquid splashes outward from the central position and forms empty holes. The average hardness of Fe Co Ni Cr Cu_0.5melting zone and 304L melting zone is lower than that of base metal. It is due to the diffusion of iron element in 304L stainless steel into the melting zone to form iron-rich phase, and the existence of different size cracks in the melting zone.