The　structural　and　properties　of　LiNi0.5Mn1.5O4-Fd-3m　and　LiNi0.5Mn1.5O4-P4(3)32　spinels　as　the　high-voltage　cathode　materials　were　investigated　by　the　first-principles　theory.　The　calculated　results　indicate　that　the　crystal　structure　of　the　LiNi0.5Mn1.5O4-Fd-3m　is　beneficial　to　the　transition　of　lithium　compared　with　LiNi0.5Mn1.5O4-P4(3)32.　Due　to　the　charge　overlap　of　LiNi0.5Mn1.5O4-P4(3)32　around　Mn,　Ni　and　O　atoms　significantly　increased　compared　with　LiNi0.5Mn1.5O4-Fd-3m,　which　form　a　stable　bond,　therefore　their　structure　is　significantly　increased.　The　lengths　of　the　bonds　of　LiNi0.5Mn1.5O4-P4(3)32　are　shorter　than　that　of　the　LiNi0.5Mn1.5O4-Fd-3m,　indicating　that　the　energy　of　the　bond　is　smaller,　thus　the　structure　of　LiNi0.5Mn1.5O4-P4(3)32　is　more　stable,　but　the　Mn-Mn　bonds　hinder　the　shuttle　movement　of　lithium　ions,　so　the　cycle　performance　of　LiNi0.5Mn1.5O4-Fd-3m　may　be　better　than　that　of　LiNi0.5Mn1.5O4-P4(3)32.　The　calculated　results　exhibit　the　band　gap　of　LiNi0.5Mn1.5O4-Fd3m　and　LiNi0.5Mn1.5O4-P4(3)32　are　0.487　eV　and　0.718　eV,　respectively,　which　indicate　that　the　eletro-conductive　performance　LiNi0.5Mn1.5O4-Fd-3m　is　better.