A　novel　quantum　key　distribution　protocol　based　on　the　entanglement　and　dense　coding　is　proposed,　in　which　the　memory　of　the　quantum　state　is　not　needed.　Every　four　particles　are　divided　into　a　group,　in　which　{(1,2),(3,4)}　or　{(1,3),(2,4)}　are　in　entanglement.　Some　of　the　groups　are　used　to　transmit　the　message,　and　the　others　are　used　to　check　for　the　eavesdropping.　In　the　message　mode,　the　authorized　party,　who　does　not　need　to　know　the　specific　location　information　of　the　group,　can　make　the　unitary　operation　to　the　first　and　the　fourth　of　the　group.　In　addition,　the　trade-off　between　the　information　and　the　disturbance　is　calculated　under　the　intercept-measure-resend　attack　and　the　entanglement-measure　attack,　which　proves　that　the　protocol　is　asymptotically　secure.　Moreover,　the　quantum　circuit　simulation　of　the　protocol　is　shown.