The　intergranular　corrosion　characteristics　of　316LN　austenitic　stainless　steel　welded　joints　with　different　welding　heat　input　in　boiling　nitric　acid　solution　were　investigated　by　metallography　analysis　and　acoustic　emission　technology.　The　results　show　that　the　resistance　to　intergranular　corrosion　of　welded　joints　deteriorated　with　the　increasing　welding　heat　input.　The　intergranular　corrosion　resistance　of　the　weld　zone　is　better　than　that　of　the　heat　affected　zone　and　the　base　material.　Five　stages　for　the　intergranular　corrosion　process　can　be　differentiated　according　to　the　characteristics　of　the　detected　acoustic　emission　spectrum,　such　as　oxidation,　passivation,　oxide　film　crack　initiation,　oxide　film　crack　propagation　and　finally　fast　intergranular　corrosion.　In　other　words,　in　the　acoustic　emission　spectrum,　there　exist　an　obvious　energy　peak　by　20　kHz　representing　the　oxidation　signal;　an　obvious　energy　peak　by　40　kHz　of　a　burst-like　signal　representing　the　stage　of　passivation　process;　energy　peaks　in　a　range　80　to　100　kHz　of　burst-like　signal　representing　the　oxide　film　crack　initiation;　energy　peaks　by　frequency　of　60　kHz　representing　the　stage　of　crack　propagation;　and　finally　a　peak　by　50　kHz　of　a　burst-like　signal　with　a　slightly　longer　duration　representing　the　stage　of　fast　intergranular　corrosion.　©,　2015,　Chinese　Journal　of　Materials　Research.　All　right　reserved.