In order to extend the life span of battery-powered wireless sensor network nodes, this article proceed from the power module, data processing module, wireless module and MAC protocols to design an ultra-low-power wireless sensor network nodes. The nodes improve the power module efficiency maximally, at the same time it utilizes the ultra-low-power data processing module and the asynchronous MAC protocol adopting a sleep wake-up mechanism. Thus it reduces the integrated energy consumption of wireless module significantly. The life span of the nodes has been increased more than three times. In a word, the design in proposed in this paper greatly cuts down the energy consumption of wireless sensor network, which has practical significance of expanding the application space and improving the application effects of wireless sensor network.