A　new　two-party　quantum　key　agreement　(QKA)　protocol　is　proposed　based　on　four-qubit　cluster　states.　Encoded　four-qubit　cluster　states　can　be　transmitted　directly　by　means　of　order　rearrangement　operation.　In　contrast　to　existing　QKA　protocols　based　on　four-qubit　cluster　states,　it　is　unnecessary　to　perform　two-way　quantum　communication.　We　analyze　the　security　of　this　protocol　and　prove　that　it　is　secure　in　ideal　conditions.　We　also　propose　the　method　to　ensure　the　security　of　this　protocol　in　noisy　channel.　Finally,　we　analyze　the　expansibility　of　the　proposed　QKA　protocol　and　propose　a　three-party　QKA　protocol　based　on　four-qubit　cluster　states.