Corresponding Author: Yan Wang, born in 1978, associate professor. Her main research interests include query processing in smart grid, sensor data management, wireless sensor networks and so on.;Qingxu Deng, the corresponding author, email: dengqx@mail.neu.edu.cn, born in 1970, professor, Ph.D.. His main research interests include Reconfigurable computing systems, Real-time scheduling on multicore/multiprocessor systems, Worst-Case Execution Time (WCET) analysis of real-time embedded systems, Formal methods in real-time system analysis.;Genghao Liu, born in 1990, postgraduate. His main research interests include data processing in smart grid.;Xiuping Hao, born in 1988, postgraduate. Her main research interests include data processing in smart grid .;Baoyan Song, born in 1965, professor, Ph.D.. Her main research interests include database, data stream processing, cloud computing, massive data computing and so on.The authors proposed an energy-efficient query based on variable region for large-scale smart grid (E2VR) to solve the problems in current smart grid monitoring systems.