In wireless sensor networks, the data aggregation is an essential paradigm for routing, through which the multiple data from different sensors can be aggregated into a single data at intermedial nodes enroute, in order to eliminate data redundancy and achieve the goal of saving energy. Some existed medium access protocols and algorithms can effectively prolong the lifetime of the sensor network by determining when each sensor should transmit its data, and when it should sleep. In this paper, we focus on applying multiple spanning trees to organize the data aggregation, which is different from these existed single spanning tree methods. At first, the problem of constructing multiple spanning trees is transformed into a linear programming problem of the data flow network. Based on the solved optimal rate between the two adjacent sensors, the two constructing algorithms of the spanning tree are presented. Experimental results indicate that the method of multiple spanning trees can be of benefit to energy saving for wireless sensor networks, and the corresponding appropriate constructing algorithm can prolong the lifetime of the sensor network.