The　adsorption　and　decomposition　of　N2O　on　the　InN　(0001)　surface　have　been　explored　employing　density　functional　theory　method.　To　study　the　most　favorable　N2O　adsorption　model,　ten　typical　adsorption　cases　(four　for　the　parallel　style　and　six　for　the　vertical　style)　were　proposed.　The　calculated　results　indicate　that　the　parallel　models　are　energetically　preferred　over　the　vertical　models.　The　parallelly　adsorbed　N2O　prefers　to　be　dissociated　on　the　surface,　the　dissociated　O　atom　is　combined　at　the　fcc　site,　and　the　N-N　piece　is　desorbed　from　the　surface　and　forms　N-2　molecules.　The　comparison　of　the　density　of　states　of　InN　(0001)　surface　before　and　after　N2O　adsorption　is　analyzed　in　detail.　Through　the　searching　for　transition　state　of　decomposition　reaction,　a　very　low　energy　barrier　of　45.0　KJ/mol　is　derived.