With　the　development　of　vehicular　networks,　the　vehicle-to-everything　(V2X)　communication　aided　emergency　warning　is　envisioned　to　improve　the　safety　of　driving　service　in　intelligent　transportation　systems　(ITS).　By　considering　the　delay　sensitivity　of　different　vehicles　receiving　warning　information,　this　paper　investigates　the　V2X　communication　aided　emergency　message　dissemination.　Specifically,　according　to　the　distance　between　the　vehicle　and　the　emergency　point,　we　divide　the　vehicles　in　the　coverage　of　the　roadside　unit　(RSU)　into　two　groups,　namely,　the　primary　priority　group　and　the　secondary　priority　group.　Then,　we　formulate　a　joint　optimization　problem　for　content　partition,　user　grouping　and　channel　allocation　to　improve　the　resource　utilization　and　the　efficiency　of　emergency　message　delivery.　The　objective　is　to　ensure　that　all　vehicles　in　the　primary　priority　group　can　reliably　receive　the　warning　messages　within　a　fixed　deadline,　and　meanwhile,　the　RSU　can　send　as　many　warning　messages　as　possible　to　the　vehicles　in　the　secondary　priority　group.　Despite　the　nature　of　mixed　integer　and　non-linear　programming　problem,　we　propose　a　layered　approach　to　solve　the　problem.　Finally,　we　conduct　simulations　to　validate　the　efficiency　and　effectiveness　of　the　proposed　algorithm,　compared　to　some　benchmark　algorithms.