The　fine　texture　and　microstructure　of　dissimilar　metal　joint　was　observed　with　microscope　and　shear　strength　of　the　joints　was　tested.　The　bonding　mechanism　was　studied　by　mean　of　SEM.　The　optical　macroscopic　experimental　results　indicate　that　the　interface　of　copper-steel　joint　deposited　by　plasma　arc　is　smooth　and　there　are　not　any　welding　defects　such　as　gas　porosity　and　crack.　Therefore,　a　weld　without　penetration　between　dissimilar　metal　is　achieved.　The　segregation　and　permeation　of　iron　is　not　found　in　the　copper　adjacent　to　the　joint　interface.　Hence,　the　phenomena　of　embitterment　can　not　occur　in　the　deposited　joints　that　is　28μm　away　from　the　joint　interface.　Mechanical　property　experiments　show　that　the　shearing　strength　of　weld　is　higher　than　that　of　deposited　copper.　The　SEM　tests　indicate　that　diffusion　from　iron　to　copper　is　more　obvious　than　that　from　copper　to　iron.　In　the　transition　region　of　deposited　joint,　the　oversaturated　α　+　ε　solid　solution　are　formed　in　room-temperature,　which　indicates　the　copper　layer　and　the　steel　body　are　well　joined　metallurgy.