A beacon scheduling method in multi-hop ad-hoc communications is provided. This method can prevent overhead in a manner that a base station (BS) transmits beacon slot information to a carrier sense multiple access (CSMA)/collision avoidance (CA) node (CN) and a gateway (GW) through contention-free time division multiple access (TDMA) communications at initial clustering, the CN and the GW performs a sequential clustering to forward the beacon slot information to a cluster head (CH), the CH aggregates joining messages from nodes and assigns non-colliding beacon slots to the nodes, and the GW uses a beacon slot frame of a beacon transmission period (BTP) used by its selected CH in a beacon reply period (BRP) as well. Accordingly, the CH does not need to separately perform the initialization to elect the beacon slot, and the GW also does not require a separate initialization to select the beacon relay slot.