Super duplex stainless steels were welded using new flash butt welding technology of temperature controlling system. The super duplex stainless steel (329J4L) and conventional duplex stainless steel (329J3L) were used. The samples were mounted in the dies using a Gleeble thermal simulator and flash but welding was made. The specimens were heated up to 1373K for 10sec, 20sec and 30sec. Flash butt welding has consisting of a two stage processes of a flash action and a contact resistance. First stage was a flash welding process and second stage was a solid state bonding process. The cross sectional microstructure of the weld bond region showed two types of a deposited fine particles region and a solid state bonding region. The grain growth was hardly observed in the weld region and the heat-affected zone. For further increasing joining efficiency of solid state bonding at the second stage, the welding time at 1373K was increased from 5 sec to 180sec. The bonding area increased with increasing welding time at 1373K and successfully welded for conventional duplex stainless steel.