Abstract: Data aggregation plays an important role in wireless sensor networks energy-efficient policy.The time control of data aggregation is one of the key issues，because it directly affects the accuracy of the data aggregation and delay.Data aggregation model is described by Poisson process and probability of data aggregation time is deducted.In order to meet certain requirements of the probability and data，a way to get data aggregation time control is addressed.Simulation shows that the theoretical analysis and simulation results are consistent.The conclusion provides a new idea to analyze data aggregation time control.