We　discuss　the　technology　detail　of　data　aggregation　in　wireless　sensor　networks　(WSNs)　in　this　paper,　which　consists　of　three　parts.　First,　we　apply　the　classical　K-average　clustering　algorithm　to　the　phase　of　cluster　division　which　is　the　first　step　of　the　aggregate　tree.　Second,　the　cluster　head　node　and　the　cluster　group　nodes　are　constructed　based　on　the　entropy　formula　H(S　g|x)Fg(c)　and　pseudo-random　function.　Finally,　we　study　the　secure　data　fusion　method　among　the　nodes.　©　2011　IEEE.