In wireless sensor network (WSN), much literature focuses on developing energy-efficient protocols. In addition, many papers propose data storage schemes but they do not take power saving into consideration. Hence, these data storage schemes cannot perform well based on energy-efficient protocols. Therefore, it is very critical to propose a data storage scheme to support energy-efficient mechanism. In this paper, we propose an energy-efficient data storage scheme in WSN. Our scheme adopts a grid-base architecture, in which each grid guarantees that two sensors will stay in active mode while the other sensors stay in sleep mode to save energy. Simulations have shown that our energy-efficient data storage scheme can reduce energy consumption.