In the present study, the mechanical and microstructural properties of dissimilar joint of 304 austenite stainless steel and C70600-copper-nickel alloy made by Gas Tungsten Arc Welding process has been investigated. The aim of this joint is using the twin metallurgical properties such as; heat dissipation and corrosion resistance of copper-nickel alloy and mechanical properties of 304 austenite stainless steel alloy. Welding of two dissimilar metal steel to copper-nickel alloy due to differences in melting point, the difference in thermal conductivity, rapid solidification of copper nickel are facing many problems. In this research due to solubility and weldability of nickel with two both alloys, three filler metals Inconel 625, Inconel 82 and 61 were used. According to microstructural investigations welds made by Inconel 625 and Inconel 82 show a finer equiaxed dendrite structure as compare as in Inconel 61 filler metal. The tensile strength of samples welded by Inconel 625, 82 and 61 filler metals was 324, 323 and 293 MPa, while the elongation percent of three samples show small difference. According to mechanical properties of joints, the Inconel 625 and 82 filler metal are appropriate for dissimilar welding 304 austenite stainless steel and C70600-copper-nickel alloy.