The present invention provides a method for finding a backup node for a node in a sensor network. Firstly, determining a node which is in a state of waiting for being an agent node among a plurality of nodes adjacent to the node to be backed up for using the agent node to find the backup node. The states of waiting for being backed up is that the quantity of electricity of the node to be backed up drops below a preset value. According to the present invention, the node to be backed up does not need to communicate with a large number of nodes. It only needs to determine an agent node among the adjacent notes to do the substantial search for a backup node.