This paper presents the design and implementation of a smart wireless sensor node,which is aimed to reduce the energy consumption of the wireless sensor network.On this basis,we set up the wireless sensor network,and realize the node-level and the network-level energy-efficiency.The node-level energy-efficiency,based on the adaptive radio frequency power,assumes that the node can reduce the necessary output power automatically and ensure the reliable communication at the same time.The network-level energy-efficiency is realized through comparing the energy consumption of star network with that of tree network and then selecting the more efficient structure.Experimental test has proved that the designed sensor node is applicable to realize the adjustability of transmission power and network configuration.