Recently,　we　first　proposed　a　quantum　deniable　authentication　protocol　based　on　the　property　of　unitary　transformation　and　quantum　one-way　function,　but　the　previous　scheme　needs　the　help　of　a　trusted　center　and　its　quantum　efficiency　is　only　25%　[Quantum　Inf　Process.　(2014).　doi:10.1007/s11128-014-0743-9].　In　order　to　improve　the　above　scheme　efficiency,　a　simple　and　effective　quantum　deniable　authentication　protocol　without　a　trusted　center　is　proposed.　Utilizing　the　method　of　key　agreement　and　encryption　mechanism,　this　scheme　can　provide　that　only　the　specified　receiver　can　identify　the　true　source　of　a　given　message　and　the　specified　receiver　cannot　prove　the　source　of　the　message　to　a　third　party　by　a　transcript　simulation　algorithm.　Finally,　efficiency　analysis　results　show　quantum　efficiency　of　this　scheme　will　be　50%　and　it　also　has　the　remarkable　advantages　of　consuming　fewer　quantum　resources　and　lessening　the　difficulty　and　intensity　of　necessary　operations.　In　addition,　security　analysis　results　show　that　this　scheme　also　satisfies　the　basic　security　requirements　of　deniable　authentication　protocol　such　as　completeness,　deniability,　and　can　withstand　forgery　attack,　impersonation　attack　and　inter-resend　attack.　(C)　2016　Elsevier　GmbH.　All　rights　reserved.