We　propose　a　new　two-party　quantum　key　agreement　(QKA)　protocol　using　five-qubit　Brown　states.　One-way　quantum　transmission　can　be　realized　by　merging　Brown　states　and　decoy　photons　randomly.　The　security　of　this　protocol　is　shown　to　resist　the　outsider　attack　and　participant　attack　over　the　ideal　channel.　Some　methods　are　also　proposed　to　ensure　its　security　in　noisy　and　lossy　quantum　channel.　Finally,　we　generalize　it　and　propose　a　multi-party　QKA　protocol　based　on　Brown　states.