PEADG　(Power　Efficient　Algorithm　for　Data　Gathering)　is　a　data　collection　protocol　of　the　meter　reading　system　based　on　Wireless　Sensor　Network　(WSN).　The　network　topology　of　PEADG　protocol　is　composed　of　a　set　of　trees.　The　root　nodes　balance　the　network　load,　and　effectively　extend　the　lifetime　of　the　network.　However,　PEADG　still　exist　some　problems　such　as:　does　not　consider　the　balance　of　the　number　of　nodes　on　multi-trees.　We　focus　on　the　problems　existed　in　PEADG,　and　propose　some　improvements　from　three　aspects:　(1)　balance　the　network　load　of　multi-tree　in　the　topology;　(2)　consider　the　residual　energy　of　nodes;　(3)　collect　network　topology　information　by　using　base　station.　The　simulation　results　by　MATLAB　tools　show　that　the　improved　protocol　extends　the　lifetime　of　the　network.