Disclosed is an event alerting system and method using dynamic local grouping for 1:N event alerting. The event alerting method for an event alerting server to transmit an event message to clients connected on a network includes a) receiving an event alerting request from clients having generated events, or generating an event by the event alerting server, b) grouping the clients according to areas with reference to a transmission distance to the respective clients according to a client list by the event alerting server, c) transmitting a client list of the grouped areas and an alerting data packet to a plurality of master clients selected by the grouping process, and d) transmitting a client list and an alerting data packet to a master client from the master client of an upper group up to the last layer established by performing the grouping process again.