Provided are a device of a node and method for beacon scheduling in an ad-hoc network and a data transmitting method thereof, which reduce power consumptions of nodes in an ad-hoc network when data communications between the nodes occur frequently. A beacon transmitting node checks its residual power. If the residual power is lower than a predetermined level, the beacon transmitting node notifies a plan to change its beacon cycle to other nodes. Thereafter, the beacon transmitting node increases the beacon cycle and transmits a beacon at the increased beacon cycles. Consequently, the beacon transmitting node can change its beacon cycle dynamically according to its power condition. Thus, the life span of the node can be increased. Therefore, it is possible to reduce an overhead of reconstructing a sensor network.