Cognitive　radio　has　been　considered　as　the　key　to　promote　the　efficient　use　of　the　spectrum　by　exploiting　idle　spectrum　bands.　Energy　detection　method　is　the　most　commonly　used　method　for　spectrum　sensing　in　cognitive　radios　because　of　its　simplicity　and　good　performance.　However,　the　performance　of　energy　detector　deteriorates　rapidly　if　the　noise　power　is　fluctuating.　In　order　to　cope　with　noise　uncertainty,　this　paper　proposes　a　robust　energy　detection　method　based　on　Huber＇s　mixture　model.　The　proposed　robust　energy　detector　performs　amplitude-limiting　operation　before　energy　detection　and　in　fact　is　an　improved　energy　detector.　A　detailed　performance　analysis　is　given　on　this　method　and　simulation　results　are　presented　to　show　the　validity　and　the　superiority　of　the　proposed　method.