The invention relates to a low-
energy consumption sleeping monitoring method synchronous relative to time of a 
wireless sensor network. The traditional method is high in 
energy consumption. The method in the invention comprises the following steps: in the stage of creating a relative synchronization table at a new node, 
broadcasting addition request network packets by the new node firstly to obtain 
synchronizing information of a neighbourhood node; then estimating 
clock skew, and linearly fitting multigroup of synchronization information of the neighbourhood node to estimate 
clock drift; and finally saving the sleeping period of the neighbourhood node, the estimated 
clock skew and the 
clock drift into the relative synchronization table; and in the stage of prediction and transmission of data packets of the node, realizing relative synchronization with a target node by the node according to the created relative synchronization table, then predicting the waking time at the next time according to the sleeping period of the node, setting a transmission 
timer, and finally transmitting data packets by a short permeable when the transmission 
timer is triggered. According to the invention, the energy overhead for sending the data packets by the node can be saved, and the 
idle time of a transmitting node is reduced, and the 
sleeping time of the transmitting node is increased.