Abstract: This paper analyzes the node’s process of backoff countdown under working at star topology，and calculate the access probability and the power consume that all probability state of nodes during a superframe.The results showed that the proportion of power is very low in the transmission state，and the power of the wireless network is decreased greatly after reduce the whole time of the reception states and vacancy states.In addition，we could achieve the low power after the reception probability is increased by reducing the number of network nodes correspondingly.

摘要： 通过对基于ZigBee协议的星形拓扑网络节点退避过程的分析，计算了在一个超帧的工作时间内，节点在各个状态的接入概率和功耗，结果表明，发射状态的功耗占的比重很小，要降低该类无线网络功耗，主要通过减少节点的接收和空闲状态的时间来实现；另外，指出通过相对地减少节点数来提高接入概率也可以实现低功耗。