The　current　crowding　effect　of　low-power　GaN　base　LEDs　was　investigated.　It　is　found　that　LED　module　(eight　LEDs　in　series　as　a　set　of　group)　suffered　voltage　surge　sometimes　presented　current　leakage　failure.　Pspice　was　applied　to　simulate　LED　module.　It　showed　the　damaged　samples　bore　more　voltage　and　power　compared　with　the　normal　results.　The　orientation　of　leakage　current　of　LED　chip　was　studied　via　Emission　Microscope　(EMMI),　the　result　indicated　the　leakage　current　intensively　spreaded　on　the　end　of　the　p-type　extended　electrode.　We　assumed　that　the　damaged　route　of　voltage　surged　through　the　quantum　well　of　LED,　and　the　un-distribution　current　led　to　the　effect　of　current　crowding　near　the　p-type　extended　electrode,　which　aggravated　the　injury　severity　of　pn　junction.　Well-distributed　current　could　improve　the　reliability　of　LED.　Finally,　the　failure　analysis　of　LED　with　differential　negative　resistance　effect　in　the　current-voltage　characteristics　was　given.