The smart grid has caught grea attentions in recent years, which is poised to transform a centralized, producer-controlled network to a decentralized, consumerinteractive network that’s supported by fine-grained monitoring. Large-scale WSNs(Wireless Sensor Networks) have been considered one of the very promising technologies to support the implementation of smart grid. WSNs are applied in almos every aspect of smart grid, including power generation, power transmission, power distribution, power utilization and power dispatch, and the data query processing of‘WSNs in power grid’ become an hotspo issue due to the amount of data of power grid is very large and the requirement of response time is very high. To meet the demands top-k query processing is a good choice which performs the cooperative query by aggregating the database objects’ degree of match for each different query predicate and returning the best k matching objects. In this paper, a framework that can effectively apply top-k query to wireless sensor network in smart grid is proposed, which is based on the cluster-topology sensor network. In the new method, local indices are used to optimize the necessary query routing and process intermediate results inside the cluster to cu down the data traffic, and the hierarchical join query is executed based on the local resultsBesides, top-k query results are verified by the clean-up process, and two schemes are taken to deal with the problem of node’s dynamicity, which further reduce communication cost. Case studies and experimental results show that our algorithm has outperformed the current existing one with higher quality results and better efficiently. The smart grid has caught grea attentions in recent years, which is poised to transform a centralized, producer-controlled network to a decentralized, consumer interactive network that’s supported by fine-grained monitoring. Large-scale WSNs (Wireless Sensor Networks) have been considered one of the very promising technologies to support the implementation of smart grid. WSNs are applied in almos every aspect of smart grid, including power generation, power transmission, power distribution, power utilization and power dispatch, and the data query processing of ’WSNs in power grid ’become an hotspo issue due to the amount of data of power grid is very large and the requirement of response time is very high. To meet the demands top-k query processing is a good choice which performs the cooperative query by aggregating the database objects’ degree of match for each different query predicate and returning the best k matching objects. In this paper, a framework that can effectively apply top -k query to wireless sensor network in smart grid is proposed, which is based on the cluster-topology sensor network. In the new method, local indices are used to optimize the necessary query routing and process intermediate results inside the cluster to cu down the data traffic, and the hierarchical join query is executed based on the local resultsBesides, top-k query results are verified by the clean-up process, and two schemes are taken with the problem of node’s dynamicity, which further reduce communication costs. Case studies and experimental results show that our algorithm has outperformed the current existing one with higher quality results and better efficiently.