Abstract: The effect of mixed rare earth (RE) on microstructure and mechanical properties of 2205 duplex stainless steel was studied by optical microscopy,tensile testing machine and impact testing machine.The results show that the proper amount of mixed rare earth could refine the microstructure of the steel,decrease the content of ferrite and increase the content of austenite after the solution treatment at 1 050℃.When 2205 duplex stainless steel contained 0.046% RE,its strength,plasticity and toughness were improved obviously after solution treatment.Compared with the steel without RE element,its tensile strength,elongation,reduction of area and impact energy had been improved by 3.91%,11.67%,24.55% and 9.10% respectively.