In order to better eliminate such phenomena as large amounts of redundant information and imbalanced node energy consumption in the covering process of Wireless Sensor Networks（WSN）

this paper proposes an optimal covering algorithm for node energy balance.By using the subordinate relationship between the sensor nodes and destination nodes in the monitoring area

this algorithm builds a network model and gives such dependence.Then

on the basis of the dependence and the probability theory

it solves the expected value of the sensor nodes in covering the destination nodes and then calculates the least number of sensor nodes required for covering the monitoring area.The experimental results indicate that this algorithm cannot only use the least sensor nodes to effectively cover the monitoring area

but also resist the generation of redundant information data

thus extending the network lifecycle.