The　intergranular　corrosion　(IGC)　behaviors　of　welded　joints　of　316LN　stainless　steel　with　different　welding　heat　input　were　investigated　in　this　study.　The　boiling　nitric　acid　method　was　chosen　to　provide　the　IGC　environment.　The　corrosion　rates　of　different　specimens　were　studied　and　the　micro-structures　of　each　zone　(base　material,　heat　affected　zone　and　weld　zone)　were　analyzed　in　detail.　The　results　show　that　welding　heat　input　affects　IGC　resistance　remarkably　and　low　welding　heat　input　can　reduce　the　IGC　tendency.　The　IGC　test　can　be　divided　into　three　stages,　i.e.　the　initial　corrosion　stage,　stable　corrosion　stage　and　rapid　corrosion　stage.　The　IGC　resistance　of　WZ　for　316LN　stainless　steel　is　better　than　that　of　BM　and　HAZ　due　to　the　beneficial　role　of　delta　ferrite.　©　(2015)　Trans　Tech　Publications,　Switzerland.