The invention discloses a thermal processing technique for a welded 316 austenitic stainless steel workpiece, involving a resistance furnace filled with an inert gas and comprising the steps of 1, increasing the resistance furnace to 250 DEG C; 2, placing the welded workpiece in the resistance furnace, and providing fireproof bricks at bottom for the purpose of supporting; 3, heating the resistance furnace at the speed of 100-120 DEG C/h; 4, when temperature measured from a different part of the workpiece by each of multiple thermocouples reaches 965 DEG C, starting to hold the temperature of965+/-10 DEG C for >/=2 h; 5, using a cooler to decrease the temperature of the workpiece from 965 DEG C to 200 DEG C at the speed of 100 DEG C/h; 6, naturally cooling, and removing from the resistance furnace when the temperature of the workpiece drops to 100 DEG C. The thermal processing technique of the invention has the advantages that residual stress of the welded 316 austenitic stainless steel workpiece can be fully eliminated, and sufficient impact toughness is ensured for austenitic stainless steel seams.