<FONT face=Verdana>In wireless sensor networks，most of the queries submitted by users are spatio-temporal queries such as “gathering the data in region A during a specified period of time”.Since the sensor nodes have very limited power supply

energy-efficient spatio-temporal query processing is an urgent problem to be resolved at present.In this paper

we point out that the existing algorithms have high energy consuming due to unreasonable query coordinator node.Then

we derive the theoretical optimal location of the query coordinator node and propose a class of energy-efficient spatio-temporal query processing algorithms called ECSTA based on the theory.Finally

the influence of node density and query region size on energy consumption is studied experimentally.Theoretical and experimental results show that our algorithms outperform the existing algorithms in the STWin framework.