Energy　efficiency　is　the　most　important　issue　in　research　of　wireless　sensor　networks　while　the　routing　protocol　plays　an　import　role　in　achieving　energy　efficiency　in　WSN.　In　this　paper,　the　deficiencies　of　LEACH　are　analyzed　and　an　improved　cluster-based　energy　efficient　routing　algorithm　called　ECHC　is　proposed.　An　election　weight　taking　account　of　the　residual　energy　and　concentration　of　nodes　for　cluster-head　election　is　introduced　in　the　proposed　algorithm.　The　algorithm　also　defines　a　new　criterion　for　non-cluster　nodes　to　choose　its　cluster　head.　Experiments　are　conducted　to　prove　the　efficiency　of　ECHC.