In order to control the ferrite and austenite percentage in duplex stainless steel welding,many researchers try to change the laser welding parameters and cooling medium,but ignore to study the influence of heat sink effect on weld strength.In this work,the effect of aluminium heat sink and varying cooling medium on the laser welding of duplex stainless steel (DSS) 2205 is studied.The 2 mm thick DSS sheets welded with pulsed Nd∶ YAG laser welding machine by varying the cooling medium (air and oil) and an aluminium plate used as a heat sink.The welded specimens tested for tensile strength,micro-hardness,distortion,microstructure and radiography analysis.The faster cooling rate in the oil quenching process enhances the ferrite percentage compared with air-cooled samples.But the faster cooling rate in oil quenching leads to more distortion and using aluminium as a heat sink influenced positively the distortion to a small extent.The lower cooling rate in air quenching leads to a higher tensile strength of the welded specimen.The objective of this work is to analyse experimentally the effect of cooling medium and heat sink in the mechanical and metallurgical properties of laser welded duplex stainless steel.