Provided are methods for automatically selecting a cluster header to dynamically configure a wireless sensor network, and encoding and sending a packet between nodes in a wireless sensor network to secure communication. The method includes: broadcasting, at each normal node, cluster header selecting information including capability information of the normal node, identification information of a cluster including the normal node, and identification information of the normal node, to neighboring nodes; and judging, at each normal node, if the normal node will be selected as a cluster header using the cluster header selecting information received from at least one neighboring node.